Problem with my bitcoin wallet In the distant 2013 I tried to deal with mining. At that time it was much easier than it is now.
I downloaded the official program (the version I did not remember), installed it on my computer with a powerful, at that time, videocard and mined.
When I decided to stop I had a bit less than 1 btc. Without having any possibility to cash it out I just saved it to my wallet.dat. I did it with the thought in mind that in some time I would restore mining on its base.
Currently, it is already 2 months that I can not restore my wallet. I installed different versions of the software from bitcoin.org, synchronized them, but the balance writes 0.

Can you help me find out the reason of the fact that in 2013 I had some money there (the rate was $ 130) but 0 at the moment?

P.S. The only person who had access to the wallet was me. I even have the exact date I used it for the last time.
First be very careful seeking help online, don't give the wallet.dat file or its contents to anyone, and don't screen share to get help.

Also, backup the wallet.dat file securely to make sure if you accidentally change the contents, you don't lose the money.

I don't use bitcoin core myself, so the following is just what I have been able to find out quickly.

So from here I can see some information about the wallet.dat file format. I believe it to be plain text, so you can just open in a text editor.

It contains - keypairs for each of your addresses that's what you want.

First, step enter each of the public addresses e.g. 1GwV7fPX97hmavc6iNrUZUogmjpLPrPFoE into a site like https://bitref.com/ to see if they have unspent outputs sent to them, i.e. a positive "balance". Only post the public addresses into a browser, they are the shorter strings, like the example I gave.

Now you know which addresses your money was sent to and that your wallet does indeed contain bitcoins and you can relax a little knowing you have all the private keys required to spend those coins.

There are several options going forward past this point, so I think you should check this first. It's safe if you don't modify the file and, again, only post the public addresses into a browser.