1234:
I have lost my job on 2nd Feb 2015 during my probezeit period and currently in the same company I am doing an freiwiliges Praktikum till May 31st.
Now,I have an normal work visa and not EU Blue Card in which it has written that I am allowed to work only in this company and my Visa expires on Nov 2015.
If I understood you correctly, you studied here and after graduation you changed from a study permit under §16 to a work permit under §18 bound to your employer. Since you were not issued a Blue Card, I'm assuming that you were earning less than the Blue Card threshold and that you were issued the work permit because the position and the salary were still considered appropriate and sufficient for a university graduate.
I see two major problems with you now working as an intern for the same company using the same permit. First of all, you were issued your current permit bound to the company based on a certain position. If you are now working at a completely different position at a different (presumably much lower) salary, your work permit might not be valid. Secondly, even as an intern you definitely need to be earning at least the minimum wage (you don’t meet the criteria for the minimum wage exemption).
Furthermore, you are also required to inform the ABH that your employment has been terminated (§82 Abs 6 AufenthG).
I don’t see any way around going to your local ABH ASAP to clear up your situation (and keep looking for a new job).