Passport 500g problem.. help plz

my passport 500 the indercator light lights up, installs mass storage but it makes a beep noise 4 times and will not come up to access drive. have alot important data on drive i need any ideas??

You may try using another USB cable, not longer than 18 inches, make sure that is being plugged directly to an USB port from the computer.  You may also try another computer to compare results. If the issue persists you may contact WD for a replacement.

What OS?

Check disk management to see if the drive is showing unallocated