truck feels like it is in neutral when shift it into reverse all forwad gears work
Check the fluid level first, if that is OK, then it might be internal to the trans. Have a local reputable shop inspect it for you.
Do like Tom said, check the fluid levels. Have you been off road or dirt or snow driving? The shift levers may have come off or are bent. If you can, look to see if all the linkage is intact and connected. If one looks bent, have it checked out.
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