I have tried the troubleshooting screen but it is of no help. I have 12 important updates that I can't download. I am using an Acer Aspire M5-581T running Windows 8 64-Bit.

Have you installed any third party security software?

You may try the following steps and check if these steps help you in resolving the issue.

Method 1: Run Windows update troubleshooter which will automatically fix some common problems withWindows Update.

a. PressWindows + W key on the keyboard.
b. Typetroubleshooting in the search tab and pressEnter.
c. ClickView all on left panel.
d. ClickWindows Update, new window will popup.
e. Follow the on screen instructions.

Method 2: Run these commands in Command Prompt (Admin).
a. PressWindows key +X.
b. Click oncommand Prompt (Administrator).
On the open Command Prompt window copy and paste the commands (all at once) – net stop wuauserv
net stop cryptSvc
net stop bits
net stop msiserver
ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 catroot2.old
net start wuauserv
net start cryptSvc
net start bits
net start msiserver
pause
c. Wait for the process to complete.
d. Close the Command Prompt.
Check if it helps.

Method 3: Run the System update readiness command.

a. PressWindows key + X.
b. Clickcommand prompt (Run as administrator).
c. In the Administrator: Command Prompt window, type the following commands. Press theEnter key after each command:
DISM.exe /Online /Cleanup-image /Scanhealth
DISM.exe /Online /Cleanup-image /Restorehealth
d. To close the Administrator: Command prompt window, typeExit, and then pressEnter.
e. Now try to run Windows update to check with the issue.

Method 4: If you have installed any third party security software, I would suggest you to temporarily disable them.

Note: Antivirus software can help protect your computer against viruses and other security threats. In most cases, you shouldn't disable your antivirus software. If you have to temporarily disable it to install other software, you should re-enable it as soon as you're done. If you're connected to the Internet or a network while your antivirus software is disabled, your computer is vulnerable to attacks.