I'm sorry to hear that Kevin, it's kind of unnormal. Have you been keeping your wallet safe, backups/seed?
Can you give us more info about what wallet have you been using?
If it was android app please go to the contact space and send us a ticket using you email with the logs of the app ok?
To identify the causes of these issues, we need reports/logs sent from the app.
Also, you should always have a backup, which is your recovery phrase.
To send a report, click the More button (bottom right at the bottom), then choose Contact Support from that menu. Choose an email app and send the email. We can then analyze that report.
Since your balance is missing and you have your 12 word recovery phrase, you can then go to the More menu again, then Security, then Reset Wallet (choose Reset Wallet from the dialog). Then the app will restart and you can then Restore Wallet from Recovery Phrase. Enter your recovery phrase. After about an hour your balance should be restored.
What does this mean "I have just downloaded the app after 2 years without use"? Did you reinstall the app? Was it installed on a different device?
how to recover funds on new computer and new wallet
Luiz I assume we are talking about dashcore wallet right?
Make a backup of your wallet first.
Install the newest version of the dashcore wallet downloadable from dash.org/downloads.
Place the wallet.dat file which you made a backup earlier and paste it (on the switched off wallet) in the appdata folder of the dashcore.
Hope that helps.