uninstall and reinstall, or try a power refresh, unplug for 30 secs or more and plug back in and let it cycle up to the mode it was in, see if tht works, do same in you have a router, but wait till one has cycled up berfoe doing the next. Any upgrades since thise started happrning, programs, power failures etc ?
Some times you get this because you don't safely remove the hardware. You can reinstall the software OR you can go into device manager and find the phone in the ports section. In there you will find your phone search for driver software update and even if it doesn't find any new software. It will still show up. Just go into your tools mass storage on your phone and connect to pc.