If it happens to you, we feel very sorry but we have nothing to do about it.
imToken is a tool to manage your private key, however, we will not store any of your sensitive information like mnemonic, Keystore or private key. What's more, your asset is on blockchain rather than on the server of imToken. imToken is different from a centralized platform like the exchange, we have no idea about the relation between one user and one address and we have no personal information (phone number, address, social media) about the owner of the address.
As blockchain is decentralized, irreversible and anonymous, it’s almost impossible to freeze account or rollback transaction. It’s different from the traditional financial institution like a bank. imToken cannot locate the hacker or freeze an address. So once it happened, please call the police to look for some offline clue.