TeslaCrypt is a virus that encrypts your pictures, movies, music and documents.
The creators of the virus then demand a high ransom be payed to get your files back unharmed.
Most of the time if you do pay, your files are left encrypted anyways, and you are out both the money you pay and your now encrypted files.
While your computer can be salvaged, now because of these evil degenerates, your files will not be saved unless you pay (and hope they send the decrypt key you need).
As always I post links to the articles I mention, you will find them below. Both Engadget and PCWorld are known to be solid IT news providers.
Please back up the files you hold dear, pictures of family, etc... If this hits you, chances of recovery are very low.
Here are some screen shots in case you think you are already infected: