All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Simply feeling drowsy and sleepy does not affect your ablution.
However, the scholars have various and different opinions concerning the sleep that invalidates ablution.
The majority of the scholars are of the view that if it is a short sleep of someone who is sitting down, then that does not invalidate ablution.
Therefore, if this is what you felt (a short sleep while you were sitting down) then your Friday Prayer is valid and you were not obliged to repeat the prayer by praying Thuhr.
However, if your sleep lasted for long, then you should have gone to repeat ablution so that you do not miss the obligatory Friday Prayer.
For more benefit, please refer to Fatwa 1579.
Allah Knows best.