By default, MATLAB is installed in the following locations:
C:\Program Files\MATLAB\R20XXx (64-bit MATLAB)
C:\Program Files (x86)\MATLAB\R20XXx (32-bit MATLAB)
Please note that during installation it is possible to select a custom installation directory for MATLAB. If you have installed MATLAB in a nonstandard location and cannot locate it, you may be able to locate it by searching your system for "matlab."