Squealing dryer

I have a maytag heavy duty dryer that my Dad bought me 3 years ago… it looks to be rather old but has ran well for years… until now. A few weeks age it started to make a squealing sound almost as if the belts are slipping. it would still dry the clothes but it was super loud doing so. I only use it once a week to do all th laundry in the house usually 4 or 5 loads. I used it all day today and made it thru 3 loads before it started to squeal. My husband got the bright idea to fix it today… but he broke it :mad: :mad: … it won’t even start now !!! He says he didn’t touch anything just took the back off:confused: I have no idea what to do now… any ideas as to what the squealing could be and what I can do to fix it ?