My safari is not working after installing iOS 9.3

It's a known issues with 9.3 and Safari (along with the mail app, and other apps)

Some have reported success going into the settings, safari, advanced and turning off Javascript. Others have said that the Opera browser is working, so you could use that as a workaround until a fix is issued. There is no indication how long that fix may take. Could be in a few hours, could be in days.

or you just have to wait it out.