Reply: The suject is a bit too vast to be fully discussed here.
It appears that your source of income is 'salary' only, and that TDS has been correctly done by your employer.
Despite the TDS done, you are required under 139(1) of the Income Tax Act 1961, to file your return, unless you are eligible for the exemptiion granted in the NOTIFICATION NO. 9/2012 [F. No.225/283/2011-ITA(II)], dated 17-2-2012 which is for the AY 2012-13.
If you do not file your return, you are liable for interest, penalty, loss of any tax refund, loss of any carry forward of loss etc.