Sounds like physical damage to the screen - you will need to have it replaced.

but how it could be physical damage? i take complete care of it. screen was not hit by any thing. Are there other possiblities for these spots? Is it possible that it will go away by it self or i only have to replace it, is the last option.??

Hi. I also have a 1525 Inspiron and I noticed 2 days ago that there is like a finger print on the screen. It's most visible on white backgrounds,  and looks as big as a thumb print actually. I have also taken care of the display (it's probably what everybody says) but the screen has not been hit at all. I even cover my keyboard before shutting down the laptop =/ Would this issue be a guarantee case?

Not unless you purchased a complete care insurance plan.

When I bought it last year, I don't recall anyone telling me about this. But anyways, if I haven't purchased it like you say, will they still be able to fix it? What do you think?

That spot doesn't look like burnt pixels; and if I slightly touch it with my fingernail both on that spot and anywhere else on the monitor, I can see those blue kinda trails from where it was touched. Just as on any other monitor.....