Most likely you made typo when you save your password on notepad.
If you don't know the passphrase there is no way to recover. Myabe you can try to brute Force if you are sure it is similar to the one you think it is.
Unless the wallet application is forked from popular wallet (e.g. Bitcoin Core & Electrum), brute force would be unpractical solutions.
But if it's forked from popular wallet, then
https://github.com/gurnec/btcrecover could help OP to brutef orce his wallet.