Slicer wise I use simplify3d and flashprint.
old style cura up to 15, wasn't totally awful, the new one is horrible. haven't looked at slic3r for a few years, but it has to be more user friendly that cura.

It is annoying that you have to have repetier to control the printer. simplify3d has a built in control panel that does everything repetier does.
Why cura and slic3r don't add a printer control panel - I don't know.

All a restore does is remove programs. doesn't mess with programs that existed before the restore point or any of your files.

If you've flashed the firmware, then the only way to put it bacl is to flash with the original firmware.
I tend to leave my firnware alone, I suspect this is why I've never had any issues with it on any of my machines :-)

The arduino is simply the driver software and what you use to flash the firmware (you mean ide right ?).
Have you checked the com port for the printer - that might have changed.

The z-height thing might just need re-calibrating.
Or you could have changed it :-)