A CRJ was flown with the 14th stage bleed valves OFF after the crew missed that checklist item. On landing they had no thrust reversers.

Narrative

Crew was told by Gate Agent that aircraft had been towed over after offloading passengers elsewhere. She stated that it was not the first flight of the day. This was confirmed by the Captain checking the maintenance log. Continued with flight. Upon final approach the Captain called for flaps 45 and before landing checks. I armed the thrust reverser switches and had noticed that we did not get the L/R thrust reverser armed status messages. The Captain said to continue with the landing. Upon reaching the gate the Captain called maintenance. While at the gate the Captain noticed that the 14th stage valves were in the off position. Once this was corrected the thrust reverser's armed. We realized that we had missed the thrust reverser's armed message on the takeoff checklist. Maintenance still came out and checked the aircraft. In the end we had been delayed 30 minutes. I believe that to avoid this error again in the future I must be more vigilant during the before takeoff checklist. For some reason I glanced over the fact that there is normally three green status messages before takeoff. I must have been complacent and thought I saw three when only the TAKEOFF CONFIG OK message was lit. Also; I must be more vigilant with an aircraft that has been towed to the gate. I don't know if the 14th stage valves were closed during towing or if they had been off all day. However they became turned off I should have caught it.