Many vertical blinds utilize a head rail cover to create a façade for the front of the blinds. This means that the housing that holds the vertical slats and the control mechanism for the strings is actually the same on both sides. You can dismount the vertical blinds and turn them around so you can mount them the other way. This will allow the blinds to open on the right side if needed.
Pull the blind cord to open the slats on the blinds completely. This helps balance the head rail as you remove it from the wall.
Inspect the head rail cover for screws. If you locate screws, remove them with a screwdriver and set them off to the side. If you do not see any screws, pull the head rail cover off of the head rail by hand.
Pull out on the bottom of the head rail then lift up on the head rail to remove it from the retaining clips.
Flip the blinds around so the side that was facing you is now facing the window.
Place the top of the retaining clip into the recess on the top of the rail then force the bottom of the head rail into the retaining clip.
Inspect the front of the head rail. It may or may not have screw holes for the head rail cover. If it does, attach the head rail as normal. If it does not, attach the head rail cover to the head rail with double-sided tape.