So recently my 2001 S40 turn singles have decided not to turn off after completing a turn as well my highbeams wont stay on... can someone please help me to figure out how to fix it!!

 

Sounds like you need to replace the turn signal switch.

Check this out...

baldy written ramblings: Volvo S40/V40 Guide: Removal of indicator/wiper stalks

You can get a diagram/part number/ price at Tascaparts.com or at volvopartswarehouse.com... Looks like the turn signal switch is PN 30899033 but best to do your own research for your model.