Where do i found file manager in SONY Xperia? I owned SONY Xperia smart phone and i inserted SD card into it with some files but i didn't found those file anywhere in my phone.No file manager in Xperia?

Also when i download anything it goes to phone internal memory, no chance to change it to SD card?
From the Sony Mobile site there doesn't seem to be a file manager included in Sony's ROM.

However, many excellent file managers are available on the Play Store.

I personally use ES File Exploerer for many years now and it is excellent.

Astro file manager is also very popular. 

Here's a search for many, many more posibilities