If I have a balance sheet and p/l account of any company of last two years and I want to prepare a cash budjet projeting it for the third year... HOW can I do it... and what are the items to be considered

For cash coming in you will need to consider your receivables accounts and your sales. This means when cash is collected from your sales. Also is the company selling any equipment during the year.

Some things to consider for your cash disbursements is your payables accounts, some of the expenses like salaries, supplies or merchandise. Also any projects coming up like purchasing new equipment, expansions, or renovations.