If the dryer hums but does not start your start switch is ok.
It could be a blown thermal fuse - which protects the dryer from overheating. It is located on the blower housing or at the dryer's heat source. The fuse can be checked with a multimeter for continuity. Pro Tip: A blown thermal fuse could indicate that you may have a restricted exhaust vent. Check it for blockages.
The door switch engages when you close your dryer's door and you should hear it click. It can be tested with a multimeter also.

I got this info from
https://www.electrafixbc.ca/appliances/dryer.html
Check it out for more info. Good luck!