Delaware state quarter that does not have the 1 in front of 1999 is it worth anything?

This is a common error called a filled die error. It happens when some grease or other crud gets into the little spaces on a die that's used to strike coins. The crud prevents metal from flowing into the space so a letter or number will be blanked out.

Filled die errors occur often enough that they don't sell for much above face value. You might find someone who specializes in collecting error coins who would pay a buck or two.