You may have been hit w/malware fake windows update or,
One or more updates may not have been compatible.
Do this w/ power supply plugged in, don't run the battery down.
Turn all security and firewall OFF.
Start>All Programs>Accessories>System Tools>System Restore,
Then select a date (if system restore has one) to restore to, and follow through with the prompts.
This sets the hard drive back to a day (the day) before the problem occurred.
If system restore is not working a virus could have disabled it.
Normally, when Windows Update Installs updates, a restore point IS created.
Now follow thru:
The system was restored to a previous date > your documents are saved, etc...
Turn Firewall and security back ON.
OR
Malware may have and...