It could just be a blown fuse .........you`ve got to figure out if its the dash unit that is bad or the sending unit in tank
If you unplug the sending unit at tank it should go to the full reading or empty....if you ground the sending unit wire it should go full ........this would indicate the dash unit is ok
Might try diconnecting battery for about 10 minutes and see if things go back to normal .......I have seen where you disconnect battery and ground the positive side for about 15 seconds and everthing resets it self nand goes back to working
good luck
bg
November 2007