I have a compaq home computer. A couple of weeks ago, it quit working. I can't get it to where I can log on or anything. I've been told I need a boot up disc. Where can I get one?

https://toolslib.net/downloads/viewdownload/1-adwcleaner/
i would run this cleaner sounds like you have malware.

First - re-seat the hard disk and reboot the computer. If the computer does not boot up then reboot and go into the BIOS configuration to see if the BIOS detects the hard drive. If it doesn't detect the hard drive then it could be faulty.
Then the hard drive needs to be replaced in the computer/laptop, Windows installed and the computer or laptop's device drivers plus your programs etc. to get a functioning computer/laptop again.

1st try boothing up with a usb keyboard if you have one available. It may be the keyboard.

are we talking about facebook or windows

When Windows Update stops working, the first thing I suspect is a virus. See if you can download and install Malwarebyte's Antimalware. Update the virus definitions and run a quick scan. If you are not able to do this, boot the computer into safe mode with networking and do it (tapping F8 while booting) Run a quick scan & delete anything it finds. Try WU again and see if it works.
Malwarebytes can be downloaded here:
http://dw.com.com/redir?edId=3&siteId=4&oId=1770-20_4-0&ontId=20_4&spi=94faea6144de2554b617b78c5e46df79&lop=link&tag=tdw_dltext&ltype=dl_dlnow&pid=11164457&mfgId=6290020&merId=6290020&pguid=C3uNrAoPjFsAACb50NIAAAAX&destUrl=http%3A%2F%2Fdownload.cnet.com%2F3001-20_4-10804572.html%3Fspi%3D94faea6144de2554b617b78c5e46df79
If you were infected, run a full scan as well.
If WU still is not working and your computer is clean, try this
http://support.microsoft.com/kb/971058
Then go here and try installing Reader v8
http://get.adobe.com/reader/otherversions/

Forgot laptop password? Crack login password!

Press F8 while booting and select Safe Mode to see if you can get video. If you do it could be a driver problem and you could uninstall the Display Driver in Device Manager and try to boot normally and look for an updated driver. Reboot into Safe Mode again and select Cancel if prompted to install drivers when restarting to avoid reinstalling the existing drivers if it fails to operate after doing so. If still having issues it could be a failing video card or motherboard if the video is integrated.

If a laptop is locked up, you have a couple options, you can unplug it, and remove the battery, or you can press and hold the power button until it turns off. I would try the second one before the first.

Boot from install cd. select reset password from utilites