Problem with my bitcoin wallet
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.