You have not given us all the details but...
Insert the windows 7 CD into the drive and select: "upgrade"
This restores the defaults in the operating system, but will not erase your personal stuff
and usually, it will make everything normal again.
Visit Toshiba website and download ALL the latest updates and drivers for your model. Even if your drivers are installed now, I want you to reload all of them, especially the graphics and audio drivers.
To load the drivers, turn off the antivirus and firewall first, load the drivers, restart, turn the security back on.