Revert all changes in Photoshop
Is there a way to revert all the changes that I made into document since I opened it?
Of course I could just close it without saving it and reopen it again, but may be there is a faster way?
This is not quite the same as reverting all history since the document opened, but: if you're just looking for a faster way than your "closing without saving" method, then File â†’ Revert will expedite that for you.
The default keyboard shortcut for this command is F12.
Adobe Help docs: Revert to the last saved version
You need to open history panel:
Window > history, and click on the first thumbnail (which is state, when you opened document)