What would cause my truck to lose all gears suddenly?

What is your question?

So when I shift I have no gears and the Indictator light also goes out but whn the indicator light does come on the gear grabs and works fine but then it gies back out I lose gears again

What makes this problem better or worse?

The gear grabs when indicator light stay on but then when the light disappears I have no gear again

How long has your 2001 GMC Yukon XL 1500 had this problem?

3 days