Hi Najshan & welcome to chordie!
I agree with Russell Harding - a professional piano tuner is what you need. Chances are, your piano is badly in need of both tuning AND regulating. Regulating is when the action (all the mechanical bits between the keys and the strings) gets adjusted.
Old pianos can be made to sound and play like new again with a little attention from a professional. Many piano tuners also deal in used instruments.
Each note on a piano has 3 strings that must be in unison. The piano's tuning must be 'tempered' - meaning that the notes are slightly 'off' so that the tuning sounds correct across the entire range of the keyboard. A piano tuner has special tools and special skills.
A piano is a marvelous thing to have - but if it is out of tune or unplayable then it is just a very large and very heavy piece of junk. If you are going to move the instrument, you can rent special wheels that strap on and make it easy to roll.
Yes, all this will cost money . . . but it is worth the investment if the piano is tunable.
"That darn Pythagorean Comma thing keeps messing me up!"
[url]http://en.wikipedia.org/wiki/Pythagorean_comma[/url]
