Scroll bar on my touchpad/mousepad not working??

I trust that you understand that scroll bars are only visible if more than 1 page is to be displayed. If you have magnified a particular page, the scroll bar may be outside the view of the screen - on the right side, Scroll to the left until you see the right border.
Perhaps you are referring to the touchpad.
The scroll feature on the touch pad is not visible. You enable the touchpad by tapping twice on the upper left corner of the touchpad. A lite will appear in that corner when the touchpad is ON.
Then the scrolling feature is enabled on the right side of the touchpad. Simply run your finger up and down the right side of the touchpad. For more information, refer to the User Guide here:
http://h10032.www1.hp.com/ctg/Manual/c02102005.pdf

you might have to reset it
Most modern laptops with touchpads offer vertical scrolling, horizontal scrolling or both. These features are located along the right-hand and bottom edges of the touchpad, respectively, and are activated when you swipe your finger along the touchpad edge. Scrolling functionality is nearly always enabled by default, but some users find the feature an annoyance and elect to turn it off. In most cases you can simply turn the feature back on using the Windows Control Panel.

Click the Windows Start button, select "Settings," and then click "Control Panel." Double-click the icon labeled "Mouse." Select the Touchpad properties tab. The labeling of this tab varies, depending on your computer manufacturer, operating system version and the device drivers installed on your machine. Common labels include "Touch Pad," "Device Settings" and "Dell Touchpad." If you do not see this option, you may not be able to turn on scrolling for your laptop; skip the remaining steps and refer to the "Warnings" section below. Click the "Settings" button within the Touchpad Properties menu and look for the section labeled "Scrolling Settings" or similar. Enable scrolling within this section and define other scroll settings, such as scroll zone width and scrolling speed. Click "OK" to confirm your changes, and then close the Control Panel windows opened in the previous steps. The scrollbar on your laptop is now enabled.
Scroll Is Not Working With Windows 7 b> Certain computer touchpads have a vertical section on the pad itself that is used to scroll through the page or program window that you are currently viewing on your computer. If the scroll functionality suddenly stops working but the actual touchpad is still fine, this means that the part of the software for the device that controls the ability to use the scroll has been disabled. You can enable it again in the Control Panel.
Click "Start." Click "Control Panel." Click "Mouse." Select the "Enable Scroll" option (or whatever similarly named option is available on your specific model of laptop computer). Click "Apply." The scroll bar on your touchpad will now work again.

b>

Most modern laptops with touchpads offer vertical scrolling, horizontal scrolling or both. These features are located along the right-hand and bottom edges of the touchpad, respectively, and are activated when you swipe your finger along the touchpad edge. Scrolling functionality is nearly always enabled by default, but some users find the feature an annoyance and elect to turn it off. In most cases you can simply turn the feature back on using the Windows Control Panel.

Click the Windows Start button, select "Settings," and then click "Control Panel." Double-click the icon labeled "Mouse." Select the Touchpad properties tab. The labeling of this tab varies, depending on your computer manufacturer, operating system version and the device drivers installed on your machine. Common labels include "Touch Pad," "Device Settings" and "Dell Touchpad." If you do not see this option, you may not be able to turn on scrolling for your laptop; skip the remaining steps and refer to the "Warnings" section below. Click the "Settings" button within the Touchpad Properties menu and look for the section labeled "Scrolling Settings" or similar. Enable scrolling within this section and define other scroll settings, such as scroll zone width and scrolling speed. Click "OK" to confirm your changes, and then close the Control Panel windows opened in the previous steps. The scrollbar on your laptop is now enabled.
Scroll Is Not Working With Windows 7 b> Certain computer touchpads have a vertical section on the pad itself that is used to scroll through the page or program window that you are currently viewing on your computer. If the scroll functionality suddenly stops working but the actual touchpad is still fine, this means that the part of the software for the device that controls the ability to use the scroll has been disabled. You can enable it again in the Control Panel.
Click "Start." Click "Control Panel." Click "Mouse." Select the "Enable Scroll" option (or whatever similarly named option is available on your specific model of laptop computer). Click "Apply." The scroll bar on your touchpad will now work again.

b>

Most modern laptops with touchpads offer vertical scrolling, horizontal scrolling or both. These features are located along the right-hand and bottom edges of the touchpad, respectively, and are activated when you swipe your finger along the touchpad edge. Scrolling functionality is nearly always enabled by default, but some users find the feature an annoyance and elect to turn it off. In most cases you can simply turn the feature back on using the Windows Control Panel.

Click the Windows Start button, select "Settings," and then click "Control Panel." Double-click the icon labeled "Mouse." Select the Touchpad properties tab. The labeling of this tab varies, depending on your computer manufacturer, operating system version and the device drivers installed on your machine. Common labels include "Touch Pad," "Device Settings" and "Dell Touchpad." If you do not see this option, you may not be able to turn on scrolling for your laptop; skip the remaining steps and refer to the "Warnings" section below. Click the "Settings" button within the Touchpad Properties menu and look for the section labeled "Scrolling Settings" or similar. Enable scrolling within this section and define other scroll settings, such as scroll zone width and scrolling speed. Click "OK" to confirm your changes, and then close the Control Panel windows opened in the previous steps. The scrollbar on your laptop is now enabled.
Scroll Is Not Working With Windows 7 b> Certain computer touchpads have a vertical section on the pad itself that is used to scroll through the page or program window that you are currently viewing on your computer. If the scroll functionality suddenly stops working but the actual touchpad is still fine, this means that the part of the software for the device that controls the ability to use the scroll has been disabled. You can enable it again in the Control Panel.
Click "Start." Click "Control Panel." Click "Mouse." Select the "Enable Scroll" option (or whatever similarly named option is available on your specific model of laptop computer). Click "Apply." The scroll bar on your touchpad will now work again.

The "Touchpad is very sensitive; if you look while scrolling, the "scroll-bar" will turn (Blue), click on the ("scroll-bar"), until it turn "Gray." Note: "You ca use the Pointer Device / Touchpad without using the Scroll-bar, basically anywhere on the screen; ("bottom scroll-pad" = left to right"), and ("right -side edge scroll-pad = up & down").

Right above the Touchpad is the On/Off button to Enable the Touchpad, or Disable the Touchpad.

If the Touchpad light is on, then the Touchpad is Enabled. (The On light is right above the Touchpad also)

Do you have the Touchpad enabled?

Since it is a Laptop you can not just go over to the Scroll Bar. Move the arrow from the mouse over to the scroll bar. Hold on the left key below the mousepad. The scroll bar should turn a differnt color. Move the scroll bar up and down with your finger,using the mousepad.

Go into your control panel (if your on windows). Load the mouse settings control. You can customize the features of your touchpad.

just reinstall the factory settings of the software drivers of ur mousepad.in case of hp laptop,it may be synaptics software drivers.

The option to enable or disable the scrolling option for the notebook touchpad is generally available by going to the Control Panel, then selecting Mouse. Within that area, go to Device Settings, select the touchpad from the list of available devices, then click Settings. There should be an option for "virtual scrolling" - click on it, and you should be given the options to turn on or off both horizontal and vertical scrolling for the touchpad control.