Hi tracy,
I am afraid that you might need to disassemble your camera and replace the broken part. See [https://www.youtube.com/watch?v=7huA4R9rXrQ|this instructional video] (the removal of the particular front piece is shown at about 14:00) or take a look at [http://www.dslrparts.com/#!how-to-replace-parts-on-the-rebel-xti/c18e7|this website].
I am not sure if Canon would be able to provide you with a brand new part, but [http://www.ebay.com/itm/Canon-EOS-Rebel-T4i-650D-Kiss-X6i-FRONT-COVER-ORIGINAL-REPAIR-PART-/281520460603?pt=Digital_Camera_Accessories&hash=item418bed533b|here] you could get it right away.
Steffen