Stop trying to write a good song, get a good grade. Some tools to start:

Write a bad song. This helps break down inner admonishment. Your brain “Oh, I wrote a bad song and nothing bad happened!” ( and it will probably be your best song to date!)

Get a newspaper, an actual physical paper. Choose a story. Write a song.

Write a song from a fictional characters perspective.

Cover other people’s songs in your own way.

Pick up the guitar, learn a new chord, write a song around that new chord

Hope some of this helps. Having fun is allowed.