I have same phone. There should be an icon at top of screen that looks like an antenna, with two arrows animated when it is trying to connect to a wifi, and the arrows stop animating when it is connected. If you have used flight mode you would first need to turn that off by tapping where the signal bars usually are, and then tapping the link for 'turn flight mode off'. Or if wifi is just disabled the icon may be the letter E in a white box. If you see the E, tap it and then tap link for Turn on wifi (a shortcut way to toggle wifi without going thru comm manager and waiting for spinning circle thingy- only you have to use comm manager at least the first time if you restart the system)

If you see the antenna icon with animated arrows or with no circle at the top, you can help it find the network by tapping the antenna icon, then it has a pop-up bubble that says connectivity, it should have 2 links, click the bottom left one (Settings), it brings up Connections dialog window, then tap network cards, watch it try to build a list of available networks, then pick the one you want. for one you never connected to before, a single tap will give you the screen to configure that network (password if needed, etc). If you've already used one before, tap and hold (like a right mouse click in pc world), and tap connect.

If you can't find any of these screens this way, you should also be able to get there thru start > settings > connections > network cards. If that doesn't do something, you may have a problem beyond my minimal expertise.

There are freeware apps called Hitchhiker, and WiFiFoFum that may also help. Hitchhiker seems to leave a large number of files behind of every network you've ever seen, and it seems to lock up sometimes but then it works anyway. The good news is you might find it easier than all this try-this-unless-that business. Just delete the cache every once in a while. the other program gives a graph of approx relative locations and signal strengths of various networks.

this whole line of thinking assumes it could be a matter of stumbling onto the right settings amidst an unrelated issue of weak signal in the public wifi you are trying to use.

if those programs look dead on arrival though you might have something else wrong.

the only other remotely conceivable issues I can think of apart from a hardware issue would be like a change in permissions for example a fee based system they've recently adopted, or unlikely but on my network I use mac address filtering and your network adapter's unique I'd# would need to be on the approved list. That would not be used on any public wifi.

On the memory card issue, I've heard of people having to remove and reinsert cards sometimes. Not had to myself.