I had a dual boot running on my laptop... I was running windows alongside ubuntu but as for now I don't require windows because most of my space was occupied by windows so i removed it via Gparted..i dont know why but I cant extend my ubuntu partition. I've given it 40gb before and as I deleted the windows os now and trying to extend ubuntu partition but wont let me do that. Please let me know how can I sort this out.
I've attached my partition image below.