Hi,
If the compare and reset doesn't help and if you have any backup of previous days, consider restoring the page architecture/page from the backup and replace in the current db

Thanks

I managed to enter debug mode, but it only cancels the last change and does not let me go back to the day before. Do you think odoo support will be able to help me in this situation? Do they have backups? Because I do not have one.

If you need to recovery the website page, you can following steps bellow:

• Enable "Debug mode"
• Select the page that you need to recovery then click on the bug button
  
• Click the gear icon near the page name then click Compare/Reset 
  
• Select the Reset Mode option then click Reset View
  

Hope this help!