• Check your camera's Owners Manual, User's Manual, or Instruction Manual to see if there are any directions for this situation. Often they will be found in the "troubleshooting" section. If you don't have a manual for your camera, you can usually find one online by googling your camera's model name followed by the word manual. If there are instructions in the Manual, follow them. If there are not, proceed below.
• Shut yourself into a totally dark room with absolutely no light in it. None. Zero. Zilch. This means a totally enclosed space with no windows or doors that aren't sealed properly to eliminate all light from outside being allowed in. What may seem like a "totally dark" room to you when you first shut the door might be revealed to be otherwise once your vision has acclimated itself to the dark environment. The film in your camera needs no such acclimation time and will be fogged if exposed to any amount of light.¹
• Open and close the camera's back. If there is any light at all present, your film will be fogged! This might reset the camera's counting mechanism. You need to be in a totally dark room with absolutely no light in it. None. Zero. Zilch. If this doesn't do the trick, proceed below.
• Most film cameras with an automatic film winder have a manual release mechanism somewhere. Typically it is a very small, recessed button on the bottom of the camera body. Press the button to release the tension on the takeup spool inside the camera.
• Open the back of the camera. If there is any light at all present, your film will be fogged! You need to be in a totally dark room with absolutely no light in it. None. Zero. Zilch.
• Gently remove the film cassette from the camera and wind the film into the cassette. The end with the smaller cylinder sticking up out of the film cassette should be turned counter-clockwise. You will probably need to turn it several times to take up any slack before the film will begin to move back into the film cassette. If you let go of the little button, the film inside the cassette may loosen up and you will need to take up the slack again. If there is any light at all present, your film will be fogged! You need to be in a totally dark room with absolutely no light in it. None. Zero. Zilch.
• If the film has been properly released using the camera's manual release button, it should roll off the takeup spool in the camera fairly easily. If there is any light at all present, your film will be fogged! You need to be in a totally dark room with absolutely no light in it. None. Zero. Zilch.
• If you need to handle the film strip itself, try to do so touching only the edges of the back of the film (the side that is away from the camera's shutter and light box as it runs through the camera). If there is any light at all present, your film will be fogged! You need to be in a totally dark room with absolutely no light in it. None. Zero. Zilch. Once the film has been developed you can clean the fingerprints off without damaging the image captured by the emulsion side of the film.
• Wind the film completely into the cassette. If there is any light at all present, your film will be fogged! If you wish, you can leave a bit of the leader sticking out. Many people prefer not to leave any leader sticking out as this might cause them to later mistake the roll in question for an unexposed roll and shoot it again. You need to be in a totally dark room with absolutely no light in it. None. Zero. Zilch.
• Once the film is rolled safely into the casette, you can turn the lights on or open the door to your totally dark room.

¹ There are some types of B&W film that are not sensitive to the far end of the visible spectrum in the near infrared range. For these, a very low power near infrared 'safe light' may be used for limited amounts of time. For undeveloped color film and most types of panchromatic B&W film, there is no such thing as a 'safe light' that will not fog your film.