We need a tiny bit more detail. Like photos, floor plans, budget…

What level is the garage? Split? Lower? There's not even a smidgen of useful information, much less a floorplan layout, included here.

As Minardi asked - what level is the garage on? There may be no direct entry from garage into house because having such would require a stair.

Mystery meat . We need pictures a to scale floor plan of the house and garage . Often the reason no access becomes obvious with pics and a plan