What legal remedy do i have to claim the leave amount and harassment?

As you have stated it is evident that your services were terminated without any real cause and no notice was given to you, you have a strong prima facie case against the company for illegal termination.

If your nature of duties would come within the purview of "workman", then you can file a case before the authority under the Delhi Shops & Establishment Act (if you are working in Delhi), who is the Deputy Labour Commissioner. 

Applicability of the Industrial Disputes Act:

The Industrial Disputes Act extends to whole of India and applies to every industrial establishment carrying on any business, trade, manufacture or distribution of goods and services irrespective of the number of workmen employed therein. Every person employed in an establishment for hire or reward including contract labour, apprentices and part-time employees to do any manual, clerical, skilled, unskilled, technical, operational or supervisory work, is covered by the Act. This Act though does not apply to persons mainly in managerial or administrative capacity,persons engaged in a supervisory capacity and drawing > Rs.10,000 per month or executing managerial functions and persons subject to Army Act, Air Force and Navy Act or those in police service or officer or employee of a prison.

Alternatively, you can file a claim petition before the authority under Payments of Wages Act. A labour court judge is generally designated for this purpose. Or alternatively, you can file an application under Section 33 C(2) of the Industrial Disputes Act. 

On the other hand, if the above in not applicable to you because of your profile and designation, you have to file a civil suit against the company for damages and compensation. You have the following points in your favour:

i. Breach of contract: No notice was given to you before terminating your services. You need to see your contract with the company as to the time period stipulated for giving the notice of termination.

ii. Violation of Principles of Natural Justice: You were not given any reasons for termination and further you were not given a fair hearing before terminating your services.

iii. Mental harassment and torture at workplace: Wherein you were asked to perform services beyond the scope of your job profile.

iv. Arbitrary action by the Company: wherein your leave encashment and proper experience letter has not been given to you.

Based on these grounds you can easily seek directions from the court to pay your leave encashment and a proper experience letter be given to you. You can even claim damages and compensation from the company for the same. 

You have to give a Legal Notice to the management for payment of financial dues, which include salary arrears, leave encashment etc.

If the management does not respond positively or does not pay in the stipulated time of 15 days, you may file a Civil suit for recovery of financial dues in the relevant Civil court by paying the relevant court fee.