What would be wrong with a washing machine if it does not spin?

The most common problem is the lid switch. On the lid, underneath side, there is or should be a small plastic pin sticking out about 1/2 inch. When the lid is closed the pin pushes down a micro switch that lets the basket spin. It's a safety feature so someone doesn't reach into a spinning washer. Sometimes the pin breaks or falls off, or the switch is bad. It should be held on with a screw on the edge of the rim. It just has two wires and is very easy to get to and replace.