Presuming everything is now in the identical locations on the new drive, you will need to set BiaB so that it knows the path to the RealDrums and RealTracks.

This is done through Options > Preferences > RealDrums & RealTracks.

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BIAB & RB2026 Win.(Audiophile), Windows 10 Pro & Windows 11, Cakewalk Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Session Keys Grand S & Electric R, Kontakt, Focusrite 18i20, KetronSD2, NS40M, Pioneer Active Monitors.