PC got affected by viruses

[Sroban Ghosh]

URGENT!
Recently I gave my hard drive to my friend. I just got it back today and it's fully infected with viruses. I used Avira to scan the hard drive and found 624 viruses. I didn't repair it on the thought losing data on my hard drive. I just don't want to lose those files.
And now it just infected my computer. I have many important data on my Pc and external HDD.

Can anyone please tell me how to remove the viruses without getting my data deleted?

 

[Dark Lord of Tech]

https://www.herdprotect.com/installers/herdProtectScan_Portable.exe
Download herdProtect ..It's FREE and uses 68 scanning engines.

Gives detailed results , so you can choose what is removed.