In box 15 fir state taxes I'm supposed to pick the state which is Nevada but it's not showing the same when I try to choose

Several  states do not have a state income tax.  So these states will not show up in certain drop down lists.   Leave boxes 15, 16, and 17 blank when you enter a W-2 for these states.

Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington and Wyoming

Nevada does not have an income tax.  Leave boxes 15-17 Blank.