go to the vet
hiscolorchanges
If the gecko is a female, there will be no lines on the belly between the back legs.
almost every gecko some names are the tokay gecko the crested gecko and the golden gecko you can tell by looking at their eyes if their pupil is a sslit they are nocturnal
u flip them over and if it looks like they have nipples their a girl and if they don't there a boy
15 yrs old
Depends on the species, most male geckos have a noticeable bulge, or large pores. It's difficult to tell until they reach maturity.
you check on line
Male geckos have a have an upside-down "V" shape (which is actually a vent) in the general area, and a bulge right before the start of their tail. You can't tell the sex of your gecko until they are six months old. Juvenile geckos all look alike.
26
my leopard gecko has also stopped eating and she is pretty old too so I think this might be the case. 19 is fairly old for a leopard gecko to live.
no
If a Gecko has a dark V shape on it's underbelly it's a boy also if they have 2 bulges above the tail.