Xiao Zhang needs to bear civil liability. 1. Xiao can't prove that Xiao Li's MP4 has been returned. Xiao Li didn't see it, and no one else can prove it, so Xiao Zhang still has the obligation to return MP4. To say the least, Xiao Zhang did put MP4 in Xiao Li's dormitory, but he had to compensate for his mistakes and lost things. 3. The General Principles of the Civil Law stipulates that a citizen who violates a contract or fails to perform other obligations shall bear civil liability. Citizens and legal persons who infringe upon other people's property through fault shall bear civil liability.