We've had a few reports from people who report their top menu bar is missing in Pixlr Editor. A few things we have surmised about this issue:
One thing to check is to see if you are in full-screen mode. This can definitely obscure the menu bar.
So far, the reports we have had like this are from Chrome users, so using another browser might be a workaround if that is an option for you.
Some people report seeing this only when opening images directly from Google Drive. If that is the same situation for you, try opening images that you have downloaded to your desktop and see if that helps.
Sometimes, it seems closing and trying to reopen an image again will make the menu bar appear again.
For now, we are still investigating this issue. It appears to be affecting only Chrome users.