Can I lay vinyl tiles over cracked ceramic tiles - can I do it myself?

If the tiles are cracked the new floor will not install correctly

Hi there, I would be a little worried about laying a new flooring over an old one that is in bad shape. You may consider buying grout, mixing it a little soupy and running it over the entire surface of your ceramic tiles, that would give you a solid flat surface to work with before applying any over top.

Yes, but vinyl will conform to what is under it. May take a few weeks but every grout line and any but a tight crack will show through. Only costs a little more to go first class and remove the ceramil.

Yes you can. This link will give you some tips.

https://www.familyhandyman.com/tiling/tile-installation/tile-installation-how-to-tile-over-existing-tile/view-all/

If the grout lines are less than 1/4 inch, you can lay peel and stick without a problem. Anything larger, where the tile dangles over the grout line will cause the vinyl either to fall and pop up on the edges or crack. Fill in all the grout lines level to the tile, then lay the tiles. This is also the process for a free floating floor and plank laminate. Good luck.