I have a txt file labelled private key, inside is what i assume to be base64 string ending with = I have a txt file labelled private key, inside is what i assume to be base64 string ending with =, is there any way I can access the wallet I assume this is the private key for?
Presuming you are in possession of an actual private key and not a random Base64 string, consider this answer to convert it manually yourself or use an external program like this or this to convert it to the Wallet Import Format (WIF).
It would be preferred if you do this in a virtual machine disconnected from the internet for security reasons.