You probably locked the translation channel. Select the model and go to window>General Editors>Channel Control. Proceed to the Locked tab and select the XYZ translations on the left hand side and press the "move>>" button, to move them to the Non-locked window. THis should do it!
SimplyMaya specialises in Maya tutorials. We offer over 1,000 individual Maya training videos, ranging from basic Maya tutorials through to intermediate Maya tutorials. Our tutorials are created by instructors with industry experience and are designed to get you up and running in Maya quickly without making it seem like hard work.