Carpet is held in place with tack strips at the edges. These are about an inch or less from the cut edge at the baseboard, and have the upward facing points angled towards the wall.
So you can get ahold of the carpet right tight in a corner and peel it back enough to see what is under there, then work it back into place.
A small bent angle pry bar would be handy, IMO
Once you get it tucked back down tight at the edges, place a wood block on the carpet and whack it a couple times with a hammer to seat the tacks again
It's going to be easier to get at it in a closet, especially if you don't have any baseboard in there. Also, if you damage the carpet, it's not as noticeable.
Great! Thanks for the info.
Or if there is a heat register in the floor, lift it and carefully pull back the carpet around it.
Steve G has the right idea. I used a pair of plyers in the back corner in my bedroom closet . Be careful the nail strips are really sharp. Ware a pair of gloves. Hope you find what you want .
Like Dee says try any floor heat registers, especially in the bathroom vinyl. I found my was not attached at all.