The Polish wideman only joined the Baggies last season, helping to secure the side's promotion to the top flight, but has struggled to hold down a role in the side this campaign so far.
Nottingham Forest came in for the ex-Hull City man late in the transfer window, and a move looked likely with both sides working to achieve a deal to bring him to the City Ground.
As the deadline passed, Grosicki was left in limbo, with no official confirmation over whether the move was completed.
However, that the move has fallen through, with paperwork submitted 21 seconds after the deadline passed - and appeals to allow the move to be completed failing.
Grosicki has now returned to the club, and has been added to the Premier League squad, and will be eligible once again to play for the club as they continue to seek their first win of the campaign.