Short story, I have this private key, but not sure at what crypto currency it belongs (surely not BTC/LTC) and I was wondering if there was a way to check if the private key belongs to a specific coin automatically without trying for each crypto (I saw that I can do it via GUARDA wallet, but it will take days). An additional point would be to get also the balance in it, if 0, makes no sense to proceed further.
Can you tell us how many characters are in this private key?
You should not enter this key anywhere online or reveal it here, but it would help if you could remember approximate year and wallets you used on your old computer.
Balance can be zero for Bitcoin, but maybe there is something left in forked coins, and altcoins if key was from multicoin wallet.