Unable to upgrade the Loadrunner version from 11.5 to 12.x


We are unable to upgrade the loadrunner version from 11.5 to 12.x.  When i am trying to install the loadruuner 12.x version, it is looking for LoadRunner_x64.msi in the previous version. Unfortunatley my customer was deleted the loadrunner 11.5 version instead of upgrade directly. Now while installing the 12.x version he is facing it is looking for

"\\mlgmuc00sap026\LR 11.5\LR 11.5\lrunner\MSI\". Also we have tried to install the same by using LoadRunner_x64.msi. But its not installing. Could you please suggest us how to proceed further.

Version:- From 11.5 to 12.01

O/S:-  Windows 64-bit