After just six minutes of Forest's 2-0 defeat at Fulham, coach Steve Cooper (43) had to substitute his two centre backs with hamstring injuries and scans indicate that both will be out of action for weeks.
Cooper is now looking to bring back Cook, who joined Forest in January 2022 but was dropped from the squad after turning down loans from interested Championship sides Blackburn Rovers, Luton, Stoke City, Reading and Cardiff.
The club now needs the league's approval to reinstate him.
"We've applied through Premier League rules to bring Steve Cook back into the 25-man squad," Cooper said on Thursday.
"We are more than hoping that it would be fine, we are expecting that to happen with the circumstances we are finding ourselves in.
"Disappointing for the guys that are injured but we have to focus on the guys that are available."
Forest, 14th in the Premier League, have also lost left back Omar Richards (25), central defender Moussa Niakhate (26) and right back Giulian Biancone (22) to injuries.
Cooper is hoping to have Cook available for Saturday when his team host defending champions Manchester City.