I think I lost everything after boot camp I tried to install Windows 10 into my Boot Camp partition.  I exited the setup and, normally, my computer restarts and I log into the Mac.

Now it's just a black screen flashing a folder icon with a ? on it.  I think I've lost everything and I'm very confused and scared. Please can anyone help me?
You have three options, they go from best to worst:


Reboot into your recovery partition by holding down Command+r, and open disk utility, and attempt to repair your drive.
Still in the recovery partition, restore from backup, which most people do these days.
Reinstall OS X, and begin taking backups so #2 will work.


Hope this helps.