For better reliability, try deleting your printer's setup in System Preferences, and re-adding your printer's driver from scratch.
As an alternative way to scan, try using the built-in app called "Preview", which provides scanning support for most printer/scanners.
Assuming your printer/scanner is on, place a document on the scanner bed and then go to:
Preview -> File -> Import from (the name of your device should complete the option)
That should open a scan window that offers a few basic options for the scan along with the Scan button.
Also, you may have a printer/scanner which uses Wi-Fi. In this case you select the menu item File->Import From Scanner->Include Networked Devices. That will scan the Wi-Fi. network. You can now go back to the File-> Import From Scanner menu and look for your scanner.