Run the Microsoft Fix-It tool as suggested by Josh, and if no joy then you should be able to restore to a point in time just before it happened.
Then re-try the Windows updates.
As for your backups, I really cannot stress enough how important it is to get yourself an external drive to back up on to. The three main issues you're likely to encounter are:
1) Hard drive failure - nobody knows when a hard drive is going to die, and if it chooses an inopportune time to do so then you could be left high and dry with all your data lost. Sure, there are things you can try should this happen but better if you don't have to go there.
2) Virus / Malware attack. A lot of malware can be removed, but there is always the distinct possibility that the only way out is to reformat and reinstall.
3) Encrypting malware - an extension on the above. You're merrily using your system and then up pops a message telling you that all your personal files have been encrypted and that you'll have to pay a ransom if you want them back. I kid you not. Usually delivered by socially-engineered email, and opening up an attachment on an email from an unknown sender, typically purporting to be some kind of invoice or tax demand.
Some of the encrypting malwares are nastier than others - look in the "Security" section of this forum for more information, but always better safe than sorry.
Back your data up ASAP.