I have social anxiety but tomorrow i have to speak in front of a large audience. what should i do? any tips please?

Speak: Deep breath if it helps you, pray if you want, speak with confidence, and see your psychiatrist and tell your experience after. Follow your dr advice. Sometimes people "forget" their difficulties and just do it naturally, as if the problem did not exist. I would not be surprised if this is one of those cases. Let me know, in any case, if you want. Go for it, i would say; just do it.

Move Up Fear Ladder!: Imagine different groups of people/audiences - people u think likely 2 judge ur performance (a) very critically; (b) somewhat critically; (c) neutrally; (d) somewhat uncritically; and (e) very uncritically. Practice speakeach type of audience (one or more people), working your way up from the least to the most critical. Once you feel comfortable with one person/group, graduate 2 next level.