Check three things: the USB cable (must support data, not just charging), the phone’s USB mode (set to "PC Suite"), and the USB port (try a different one).
Several developer forums have packaged the standalone driver. Look for a file named:
File size: Approximately 3-5 MB. If the file is much larger, it may include unnecessary bloatware.
Cause: The phone is in "Charge only" mode. Fix: