Keyboard is not working properly-some of the letter keys also have numbers and when I type in a letter the number is coming up

More information is needed.

Has anything been spilled into the keyboard? Has anyone eaten over or near the keyboard?

Brush between and under the keys with a soft trim paintbrush.

Advise of the results and supply more information.

You may have hit a certain combination of keys on your Gateway laptop and turned on the NumLock function accidentally. The result is that the rectangle of keys from the 7 key down to the question mark key have become a number-entry keypad. Worse, Gateway manuals don't discuss this function.

Hold down the "Fn" key on the bottom row of the keyboard, and press the "NumLk" key. Type the letters UIO. If they come out as numbers, move on to the next step. Hold down the "Fn" key and press the "F11" key. Type the letters UIO. If they come out as numbers, move on to the next step. Hold down the "Fn" key and press the F11 key and "Scroll Lk" key simultaneously. Type the letters UIO. If they come out as numbers, move on to the next step. Hold down the "Fn" key and press the "F9" key. Type the letters UIO. If they come out as numbers, move on to the next step. Hold down the "Fn" key and press the "Scroll Lk" key. Type the letters UIO. They should come up as letters. If none of these help, then it's probably a keyboard malfunction and you'll need to get it repaired.

Your numlock is turned on. There is more than one way to turn it off.Find a USB keyboard, and plug it in. Then push the numlock key on the USB keyboard to turn it off.OR, if you don't have access to one of those, hold down the fn key (lower left hand corner of the keyboard) and press the key with numlock or number lock written on or near it.

Hold down the Fn Key and tap the F3 key (This will turn the Num Lock on and off)

check your keyboard: T and 5 are relatively close to each other. Try to clean the area under keyboard buttons especially these two buttons. may be it can help you.

one of the F keys turns certain keys on the right side to number keys, so it can act like a full size keyboard with the 10 key panel on the right.. Look carefully at the F keys to determine which one it is. Or consult the manual.

When the RH side of the keboard types numbers instead of letters then the Num Lock (number lock) key has been pressed.
Press the Num Lock Key again to return to letters again, usually this is usually done by pressing the Fn key plus and probably the Scroll keys, this key will be also marked NumLk, and there will be a LED light that will indicate when the number lock is on.

go to my computer>computer hardware>keyboard
click driver, then check if your device is working properly, if it is, click update driver.

With my IBM Thinkpad, I had to hold Shift+ScrLk to turn off Number Lock.