Obviously impossible to diagnose properly on line but I would suggest looking at the following:
1. Corrosion on the contacts - very likely if not been used for a long time.
2. Motor seized - try spinning the platter by hand as you move the arm and see if that starts it up. If it does, let it run for a good long time.
3. Cracked solder joints or defective component - you will need to search for this one.
4. Check the belt is on!