You are probably the best source of ideas for what to write songs about, and hopefully inspire yourself.
You have lived long enough to be reading this, therefore you have all your previous experience to write about.
In each of those experiences you had your own viewpoint about them and that is worth exploring.
So, get out a pen or a computer and note down those experiences. One or more will be worth writing a song about. This may take a few hours if you haven’t done it before.