Hi. Yes, the answer is to replace the pipe that your friend cut. The piece is called a sink tailpiece. It's usually 1 -1/2" and is either chrome plated brass or pvc.. You can get it at any hardware store. You buy it a little long and cut it to length with a hack saw (cut the end that doesn't have the lip). There is a nylon gasket that will go between the tailpiece and your drain basket.

Note that when you measure for length, you will need to add on the part that slips into the pipe below it.

Thank you for your help and reply