You really need to give more information. A full screenshot - image + layers + tool options always helps.
The most common user errors:
(1) The move tool is in the wrong mode - It should be in Layer Mode - the left side icon
(2) Trying to move the wrong layer. - Make the required layer active in the layer dock.
(3) When a layer contains transparency, often a text layer, the cursor needs to be on a solid pixel, otherwise the tool finds another layer with a solid pixel, often the background layer. If you have trouble with that, enable Move the active layer in the tool options.
Don't know your Gimp version? Look in Help -> About. It is there in big letters.
With recent Gimp versions there is also a layer lock, the middle icon top of the layers dock. Make sure that is off.
The most common user errors:
(1) The move tool is in the wrong mode - It should be in Layer Mode - the left side icon
(2) Trying to move the wrong layer. - Make the required layer active in the layer dock.
(3) When a layer contains transparency, often a text layer, the cursor needs to be on a solid pixel, otherwise the tool finds another layer with a solid pixel, often the background layer. If you have trouble with that, enable Move the active layer in the tool options.
Don't know your Gimp version? Look in Help -> About. It is there in big letters.
With recent Gimp versions there is also a layer lock, the middle icon top of the layers dock. Make sure that is off.