Help with lemon plant...!! ASAP

Hi folks..
I had grown a lemon plant from seed about 3 months ago
it grew just fine. ..
but now days its cotyledons are drying & getting Brown colour...
the true leaves seem to be okay...I water it correctly
it is in bright Window silt..
the pot size is also gd..
What's the matter? ?? plz help..

 

It sounds quite normal. The cotyledons have served their purpose and are now being shed.

 

man the true leaves have also started to brown...

 

A picture might help.

 

What is the matter ..??
when ever I try growing citrus- lemon & orange. ..
either they don't show up or die within 3 month s...

 

If that is the case it may be worthwhile to review suggested citrus cultural guidelines against your own to see if anything can be improved upon. By the way, if available, cuttings would be the better way to get started with. Lemon cuttings are very easy to root.