Files wth a “.nppp” extension, is a sigh of the STOP/DJVU ransomware.
You can read about it on this page.
Upload a ransom note and/or sample encrypted file to identify the ransomware that has encrypted your data.
id-ransomware.malwarehunterteam.com
Submit a sample of a file for review.
You will get a confirmation from them.
From what we know now, your files are not recoverable.
Your only solution would be to restore the files from a good backup if you have one.
The compromised files can be transferred to a CD or Flash drive.
Should a solution be found in the future you may be able to restore them.
Good luck.
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