I need help with metamask, i have some old erc-20 address(public, lost private key) and i have 400UNI on.
If the private key is lost, it will be difficult to solve this problem, unless you have stored two important things such as words and phrases when creating a wallet, or backup keystore files.
he does not need an expert, he just need his mnemonic phrase, if the wallet is created directly with metamask, since metamask will not give private keys, unless asked through procedure that was explained earlier in the topic, when creating a wallet, you do not get private key, just mnemonic phrase
i presume that OP did not asked for private key, and do not have it, but probably has mnemonic, and that should be looked for
or the problem is too simple, that he just have to switch wallets in metamask, use the pie in the right top corner