It's a bug in the latest Android software release from Sprint/HTC. If you have Mobile Network enabled, the phone won't connect to WiFi. Here's the workaround:
It should connect to WiFi now. Of course, if you leave your house where the WiFi is, it won't connect to the mobile network unless you reenable it. Painful, but it works.Sprint and HTC should fix this, if they cared more about their customers.
I did these things and it still doesn't work. Nothing wrong with my wi-fi cuz my laptops connect fine. It won't let me delete the connection only "forget." It keeps cycling through "obtaining address" and "remembered, secured with WEP" then doesn't connect. Not sure what's going on.
hrm. when you say update are you meaning the maintenance release or updated to Gingerbread? if it was to the second one the only thing i know changed wifi wise was you could no longer use wireless "N" with this phone.
only other thing i can recomend is pulling your battery for at least 3 minutes. power it back on. pull up your wifi. hit the reset button on the side of the router and then hit search again on your phone.
post either way if it works or doesnt.
android phones have differnt updates that run their system basically. <~non tech speak. the last version we had was called froyo. the current one we have is called Gingerbread. the updates are to help improve the functions of the phone and so on. to see what version you have pull up settings-about phone-software information. the Gingerbread version you should have or the current one is 2.3.3. the software number to be up to current should be 4.54.651.1. if you dont have those then you'll need to go to settings-system updates-HTC software updates. if it says nothing is there then you might have to go into a sprint repair store and have them push it into your phone with their computer.
Check out a fun infographic that teaches you how to increase storage, enhance security, improve battery life and clean your device.