1993 Ford Explorer radio

Electrical problem
1993 Ford Explorer 6 cyl Four Wheel Drive 74000 miles

i have an am and fm with a cassette player. The am works fine. But I dont get any fm stations. I dont understand why. It use to play stations fine. I tried to tune the audio, base treble and fade. But fm will not come in. My husband says, that it is impossible.
to have am and not fm. Can you help. I also want to thank you so very much for a question you answered about my smog test. I am so very grateful for your response. I'm so vey sorry that I cannot donate at this time. But financial situation is not too good at this time. But do plan to in the near future. Thanks again so very much. You guys are wonderful!