I remember that I exchange currency in web currency exchange. There, maybe saved wallet address? If I find the wallet address, what I should be done next?
Also try checking your emails, as many exchanges will send a confirmation email with the details of every withdrawal or transaction you make.
If you find the address you sent coins to, check if that address is visible in your Electrum wallet. If it is visible, then your seed phrase is correct and you either have a sync problem or your coins have been moved/stolen. If it is not visible, then most likely you have restored the wrong wallet, barring some unlikely scenarios with gap limits and the like.
Did you use Electrum to create the seed phrase in the first place back in 2017, or did you create it somewhere else and restore it to Electrum? Do you remember setting a passphrase, which is a word or phrase in addition to your seed phrase?
Nothing is lost, you have to create a new wallet and in that step choose legacy wallet.
This only applies to BIP39 phrases. Electrum phrases have an address type built in.
In 2017, when I create the wallet, I make a screenshot with seed, and now I find this screenshot and try to restore my wallet with a seed