I got this bright spot on LCD. I wiped whole screen with wet tissue paper. The bright spot is gone but now whole screen looks as if it was scratched; it has these brighter smear marks on. I don't believe it's scratched. How should I clean it?

Most every electronic store carries wipes for this kind of thing. Don't use tissue, it leaves fibres in the screen. Don't try using canned air, either, as it will force the fibres into the crevices in the sides. Use the pre-made wipes, or use a wet pad made for cleaning eyeglasses.

By "pre-made wipes" you mean the llens wipes in the wet packs?