Wont Delete Any Songs

I’ve had my Sansa Clip + for at least 6 months and now it wont let me delete any of the songs I have added and I was wondering if anyone knew why I cant delete any of the songs I’ve added. Thanks to anyone who has an answer. 

It would help if you said HOW you are trying to delete them.

What do you mean HOW?

I push the delete button of the song I want deteted and it wont delete