If I leave work for matenity reason and After I come back, can the Company say "i don't have a job, when I return to work?

If your maternity leave was covered under the FMLA, and you returned within the 12 week period allowed under the FMLA, then the university would have to return you to your prior position.  There are a few exceptions to this such as if your position would have been eliminated even if you never took any leave.  You would qualify for FMLA if you worked there at least 12 months and worked full time or at least 1250 hours during the last 12 month period.  I recommend that you meet with an attorney who can explore your facts in more detail.