How to open or rectify a PO that was cancelled by mistake ?

Hi,

Our user cancelled few POs by mistake. What are our options? Below are the two things we tried

1) Create a new PO by 'COPY FROM REQ'. But we were unable to see any reqs that we can copy from. Is there some logic that prevents reqs to be copied ?

2) Create a new PO by 'COPY FROM PO'. but the PO does not link to the original REQ. how to link the PO to the REQ ? will this cause any matching issues ?

Thanks