Go to your local hardware store and purchase another pull switch for a ceiling fan. If it is a light switch it only needs to be the type that has two positions(on and off). If it is for the fan then you will need a three position switch. Made sure you turn off the power before attempting to replace it. It will be pretty straightforward, match the same color of wires and connect with wire nuts. If the colors do not match then refer to the instructions on the switch package. Hope this helps.

I like to take the old switch with me to make sure the new one will fit in the same hole/slot. You should have no trouble finding a match.