Electrum won't recover full balance

[hosemary]

I don't know where they came from because I am sure I didn't generated that many addresses.

Those addresses are all generated from your seed phrase.
Note that electrum generating those addresses doesn't mean you generated them before. You can import any other seed phrase into electrum, and it can derive a very large number of addresses from it.

Locate the last transaction and copy the addres.. goto the console tab and type ;

Code:

wallet.get_address_index("the last txn address you copied ")

That should give you the index as the second value , copy it and extend the gap limit upto the index you copied.

This won't help.
That command gives you the address index, only if it has already been generated by electrum.

Pretty bad; it seems that it is deeper than 100k addresses.

I highly doubt OP generated such a large number of addresses.
If OP increased the gap limit to 10,000, but the address he is looking for still hasn't been generated, the problem is probably something else, and not the gap limit.

I planned to install Bitcoin core on my computer and set up watch only wallet and check addresses directly but it seems that it is unavailable for download:

Don't waste your time with Bitcoin Core. It won't help you.

[ovcijisir]

I figured out what happened in the end. When I generated last batch od deposit addresses I accidently replaced one word with another word of similar meaning. For some reason Electrum still generated wallet (don't have any idea how it passed checksum check?). That way I had two wallets.

The wallet with small amout was incorrectly generated wallet with one wrong word.
Today I got my hands on memory stick with seed backup and re-checked seed words and realised the mistake.

I am sorry guys for causing distress. But this was good learning opportunity for me to use Electrums advanced settings and learn something new. And thank you all for all the help you provided.

[hosemary]

I figured out what happened in the end. When I generated last batch od deposit addresses I accidently replaced one word with another word of similar meaning. For some reason Electrum still generated wallet (don't have any idea how it passed checksum check?). That way I had two wallets.

When you check BIP39, Electrum still generates a wallet even if the seed phrase doesn't pass the checkum. Electrum warns you about the wrong checksum, though.
Either you didn't notice Electrum's warning or your seed phrase still had a correct checksum. Even if you select the words randomly, there's still a 1/16 probability that you end up with a valid BIP39 seed phrase.

[ovcijisir]

I figured out what happened in the end. When I generated last batch od deposit addresses I accidently replaced one word with another word of similar meaning. For some reason Electrum still generated wallet (don't have any idea how it passed checksum check?). That way I had two wallets.

When you check BIP39, Electrum still generates a wallet even if the seed phrase doesn't pass the checkum. Electrum warns you about the wrong checksum, though.
Either you didn't notice Electrum's warning or your seed phrase still had a correct checksum. Even if you select the words randomly, there's still a 1/16 probability that you end up with a valid BIP39 seed phrase.

I haven't noticed any warning and I re-constructed wallet at least 10 times yesterday. I guess I had "luck" to generate wrong wallet with correct checksum. Thanks for explanation, it is good to know that.

To be honest I thought that these protections are more robust. 1 in 6 is pretty realistic chance to get correct checksum.

[hosemary]

I haven't noticed any warning and I re-constructed wallet at least 10 times yesterday. I guess I had "luck" to generate wrong wallet with correct checksum. Thanks for explanation, it is good to know that.

If the seed phrase doesn't pass the checksum, Electrum displays a message saying "BIP39 checksum failed". If Electrum didn't display that message, you are right. You still had a valid BIP39 seed phrase.

To be honest I thought that these protections are more robust. 1 in 6 is pretty realistic chance to get correct checksum.

You misread my previous post.
The probability of having a valid BIP39 seed phrase is 1 in 16, not 1 in 6.

[nc50lc]

To be honest I thought that these protections are more robust. 1 in 6 is pretty realistic chance to get correct checksum.

Although it's not entirely an issue with Electrum since you're using a BIP39 mnemonic.

In comparison, Electrum has higher bit of checksum in a form of "version number", e.g.: 12 Bits for the default SegWit seed phrase (1 / 4096).
Plus it wont generate a valid BIP39 mnemonic to prevent scenarios similar to this.