I have an RO system under my kitchen sink that I use for drinking water and ice cubes. Recently changed all the filters and 1 month later I have virtually no pressure. Can't make ice or use for drinking... please help

A month is way too short for a new set of filters but check them anyway. You might have had some debris break loose and now its caught in your filter. Also, check and confirm that you have strong pressure still feeding the RO unit. There is usually a smal shut off valve prior to the unit tapped off your other cold supply line, open that connection with the valve close. Directed the line into a bucket and turn the vlve back on to confirm pressure.

Make sure you have opened the small shut off valve on the storage tank all the way. Also, look for kinked lines.

Usually, RO system slows down when filters are dirty. Make sure you installed correct density filters and in the right sequence.

Milo is right, the shut off valves, and lines are the first things I would check. Then, did you use the correct membrane? Several membranes are interchangeable. However, if the correct one is not installed to match the drain line flow control, too much or too little water will go to drain. And, consequently the improper amount will go to your storage tank.
Al