Does the text start with "U2F" and look something like this:

If so, then it could be a MultiBit .key file... which means it is AES256 encrypted text... if you don't know the password, then you'd have to attempt to bruteforce it... which could be problematic if your dead friend used a long complex password.

Your options would be btcrecover (https://github.com/3rdIteration/btcrecover/) or hashcat (https://hashcat.net/hashcat/) and use the "multibit2john" script to extract the hash from the .key file and then bruteforce the hash using hashcat.