Quartus not recognizing VHDL functions in 2008 version of ieee.numeric_std

Why don't you just switch your compiler settings over to VHDL-93 or 2002?

Go over to assignments, settings, then just change the compiler, and recompile. If you have problems then, you may have corrupted the libraries. If you need support in the 2008, then you'll need to buy the Professional edition, as it also supports the new floating point routines that are missing in the 2002 (and 93) version. You can also use Altera- ModelSim to compile your libraries and code.