Short term

You can do Microsoft (MCSE) or Cisco certifications (CCNA) or Big Data courses (Hadoop, Python) or Business Analytics (R, SAS) and so on as per your interest in that domain.

You can opt for CIFA course.

Hi Rizwan,
There are a lot of courses available, please find all in the link mentioned below:
http://www.mapsofindia.com/my-india/education/job-oriented-courses-after-mechanical-engineering

Dear Avi,
There are lots of course available. You can do instrumentation design course, in this course you will learn field instruments specifications and detailed engineering of PLC.
1. Input/output (I/O) listing.
2. Review of P & I drawings.
3. Final loop diagrams and interlock schematics.
4. Instrument index.
5. Preliminary interlock diagrams.
6. Junction box schedule and preliminary cable layout.
7. Technical discussion and recommendation for placing orders.
8. Specifications of PLC panel.
9. Preparation of bid documents for PLC panel.
10. BOQ for erection tender, typical installation drawing.

You can opt for courses like CFA, CFP, CWA, CCRA, and CCAP.

Hello Shubham,
First choose a field in which you want to go among testing, coding and designing.
If you want to go into testing then you can do a certification in the same. All testing courses are of 3-6 month of duration.
If you want to go into coding (development) then you can pursue a certification course on your choice in any of the languages including Java, VB, C#, Advance C, PHP, Asp etc.
If you want to go with designing, you can pursue courses like web designing, basic animation, graphic designing, advanced photoshop etc.

Hi
There are many courses after B.com. You should opt for the course in which you have interest. You can pursue certification courses like Tally, ERP, Taxation Course, cost accounting, and corporate accounting. These courses belong to commerce field. If you want to pursue an animation field, then opt for some Diploma course.

You can do corporate law.

You have a keen interest in computer science, so you can learn C+ , Java, etc. because in future when you are in college, and later when you will get a job, it will help you to excel in your field.