how to reduce my thumbnail size, i made thumbnail size 4x3 inch size, but i forget from where i altered?

Answer 1

Presuming that u are using Microsoft Windows XP (or upwards).
Try opening the image in "Microsoft Office Picture Manager" and select "Edit Picture" from the toolbar.
Once done, change the Picture size by selecting the "Resize" option ....
Annnnnnnnnnnd ... hv fun ;)

Answer 2

1. may be in MS paint.
2. Open the thumbnail and see which program opens it.
3 or try Irfanview from www.grisoft.com