Sony Ericsson WT19i doesn't detect my wifi network When I bought the phone and tried to connect to my wifi network it worked fine, but after 2 days, I don't know why, it just doesn't detect my wifi network.

When I go into Settings-&gt;Wireless &amp; network Settings-&gt; Wi-fi settings my network doesn't show up there. Lots of other networks appear there but not mine.

I tried configuring manually with SSID WPA/WPA2 PSK and it says not in range. After this I tried rooting phone but still no luck.

I have a Galaxy SII and 2 other computers working correctly with my network. What's causing the WT19i to be unable to find it?
Check this forum out, since you're rooted now:

SGS2 I9100G keeps disconnecting from WIFI after installing firmware XXLPQ

Try installing a new kernel (usually found on XDA).