Any matrix can be inversed. See the link
http://web.mse.uiuc.edu/group/downloads/Aftab/Vufoils%20from%20Hang%20Xiao%202-2-10/euclid.bsmsp.1200514113.pdf
In case of non singular square matrix it is done by the most recognized method.( Butb thgat does not mean only non singular matrix can be...