Hi Gabriele,
If this happens again and you open a blank installation, you can connect to your company and all the information should be restored.
You can do this by the following:
1. Open a blank standard Accounts
2. Select the Enter Company Info icon
3. Select the button Connect To Company
4. In the Identification field, you can search for your company name
5. Once you find your company name, highlight the company you would like to connect to and press the connect button.
This should then connect you to the correct company and all your data will once again be accessible.
Kind regards,
Tayla Anniciello