You might suggest that I should use Win32::DriveInfo but for some technical difficulties I can can not use it.

The solution is obvious, resolve the technical difficulties

 cpan Win32::DriveInfo

 cpan -fi Win32::DriveInfo

A Guide To Installing Modules

Yes, even you can use CPAN

A Practical Guide to Compiling C based Modules under ActiveState using Microsoft C++

http://search.cpan.org/author/GSAR/libwin32-0.191/APIFile/File.pm#getLogicalDrives

list drives -> list of drives