If you are unfortunate enough to have picked up a CryptoLocker infestation, there is no known way to recover your data short of paying the ransom. Be careful as the price goes up substantially if you do not pay by their initial deadline. On the other hand, if you were lucky (a relative term here) enough to catch some other ransomware variant that does not actually encrypt your data, you should be able to recover your documents without paying.
As others have said—and this is not intended to be condescending—regular backups are critical as they provide an extremely simple solution to these types of issues. Unfortunately, most people do not realise just how valuable a backup can be until after they already need one.
Good luck.