Mr.Kameswarao has given valuable advice. Kindly follow it.
If the employee submits resignation without mentioning the notice period or effective date of resignation the company may accept it with immediate effect. Since employee has not tendered any notice company can recover notice pay.
Usually this is the trick/technique applied by Pvt. Insurance companies. The employee is asked verbally/on phone by bosses/HR to submit resignation and no notice pay shall be deducted. The ill informed employee becomes a game and is taken for a ride.
If the employee has mentioned period of notice/effective date of resignation in notice of resignation and if the same is accepted before effective date of resignation, it can be termed illegal. If the resignation letter was collected under coercion or by force employee can withdraw the same and lodge a complaint.
It is always better to consult elders in the family, competent and experienced well wishers, lawyer/law firm before signing a document than blindly signing a document without understanding repercussions and repenting later.