I brought a pet bit when I named her the pets colours changed and I cant fix it

https://www.sylestia.com/view/pets/?petid=5359076

Please how can I return her to her former self

It looks like you updated her colours to the correct theme colours. There would have been a green button under her picture that said something to the effect of 'update to new theme colours'. When that button is clicked, it reverts themes and purebred offspring back to the true theme colours (or updates themes with old colours to their new palettes). As far as I know, the only way to switch a pet back after you have hit this button is to redye it.