Once again, the country has been attacked by cyber criminals.
This type of attack is known as ransom-ware, which encrypts the files on your device and charges a ransom to obtain a key to unlock the files.
Do you need to pay?
No, if your files are not particularly important to you (documents, apps, photos, etc.), you can in most cases re-install your system software to the state it was initially supplied to you.
If this is not viable and you have backups of your files, then you need to identify your last ransom-ware free set and do a full restore of all files and programs (possibly after reformatting your system).
Once you have your data back again, be sure to get all the latest updates for your system software and install a good anti-virus software.