Termination Matter

Dear Sir/ Mam
This is Sushilkumar trustee of an SFI.
Kindly give me some information about termination and resignation.
In case if a candidate( have been working for more than 1 year. ) is sick for a week and have submited medical certificate, can he/she be terminated with reason of absenteeism?
If a candidate (probation) having experience of more than one year, whose contract was over in the month of Dec 2012 and contract was not renewed in written and after that one year has passed can relieving letter be issued?
Is it unlawful to continue working without renewing contract?
In this case, What should be the termination procedure?

If the candidate was absent due to sickness, and has submitted the medical certificate stating the sickness, then how can the employer terminate the candidate for the reason absenteeism
If the contract is not renewed but the contract work was on and a remuneration were paid, it is deemed as the contract was renewed for further same period. Like if an amount is deposited as Fixed Deposit and if the said deposit is not withdrawn on the expiry date or renewed the FD get renewed for further same period automatically as per my view