UPDATE: I've tried the Mnemonic Code Converter, unfortunately I was not able to find any of my address from that wallet. Definitely I will try other settings for that tool tomorrow. Thank you all who involved.
Don't do that. You shouldn't be entering your seed on any sites! Your seed should always be kept secret.
Please open your restored wallet in electrum, press ctrl+A to bring the addresses tab into view and then tell me whether there are any familiar address listed there.
Also what version of electrum did you use to originally create this wallet? 2.7.18?
Did you increase the gap limit of your wallet?
The wallet was created with electrum 2.6.4, The gap, indeed was increased, after restoring the wallet I've increased it again with 1000 as I did it before. No luck again. I really want to understand what happened with my coins and how to avoid this particular situation in the future.
Are you sure that 1HtDHigRkCPs1Ux6MPhXZ3N85i6ASnm1uA was previously in your wallet and that Electrum was showing your coins?
If so, it sounds like you restored the wrong seeds as the wallet.is_mine command should have returned true if you owned that address. Is it possible that you have multiple seeds and restored the wrong ones?
I am 100% sure I restored the correct seed. Before I've started the transaction, my balance was 5.45887085. Next I made only transaction and it was 4.368099. So "1HtDHigRkCPs1Ux6MPhXZ3N85i6ASnm1uA " would be a change address if I understand it correctly.
After restoring my wallet from seed I've noticed that my last transaction was -5.45887085 and my balance is 0. Before hardware fail the last transaction displayed was -4.368099 and my balance 1.09077