MP4 player picture probs??

[loosie]

Hi,

Hoping someone can help... Have a generic MP4(no instructions) & just loaded a number of songs pics & couple of vids on it, for daughter's birthday. Music all seems to work fine, vids I'm guessing are wrong format for it, because they don't even come up on the menu. If that's the prob, I know how to change it, but not sure of appropriate format(presume MP4 tho).

But the pictures ~ they are all jpg except one, which is png. All bar png worked fine when I loaded them straight off my computer, but many of them were the original size from my camera (1200mb+) & took ages to load. So I resized many of the pics to under 150kb & replaced them. Now they don't work. But also a couple of the smaller ones I didn't replace now don't work either, and I've tried replacing them with the originals too, to no avail. They all just come up as repetitive coloured lines. Even tho when it's plugged in the pics in that folder come up fine on the 'puter. Can anyone tell me what might be wrong & how to correct it??