Where did the toolbar go?

After coming back to using the notebook after a couple months of idleness, I realised that the toolbar was gone. At first I couldn’t remember when that could have happened, but then I thought that perhaps it was because of the jupyterthemes package I installed. However, even after uninstalling this package, the problem persisted (see picture), and although I’m a complete anti-talent when it comes to these things, I have tried clicking “Toggle toolbar”, but still nothing.

Please explain to me where I’m being stupid and what the problem is! Grateful for any help I can get!