B737 First Officer reported the landing gear failed to retract after departure but was able to successfully raise the landing gear after leveling off and following the QRH.

Narrative

On departure out of ZZZ while acting as pilot flying I called for gear up. After a few seconds we noticed the gear indicators were not showing it up. All red and green lights were on illuminated. I turned the automation on and the Captain made ATC aware of our situation. We decided to get a level-off at 10;000 ft. and vectors near the airport in case we needed to return. I handed the aircraft to the Captain and I ran the landing gear fails to retract" QRH that led us into the "gear disagree" QRH. The QRH led me to recycle the manual gear extension door; lower the handle; and then raise. This procedure successfully raised the landing gear and we continued to ZZZ1 after letting Dispatch know as well as an ELB (Electronic Log Book). Upon landing we called Maintenance to inform them of the write-up. During my preflight procedure I ensured the door was down as I am aware of this problem happening sometimes. I am not sure if something popped loose during the takeoff roll; but during my recycle attempt per the QRH it was closed and appeared to be locked."