Rita, you probably are going to have to take that tile out and replace it with a new one
Hi Rita, Here is a video that shows how to do it. It shows a pretty easy to do remedy for fixing the cracks.
Clean the area thoroughly.
You’ll need to prep the crack by evening out the surfaces and roughing them up a little so the epoxy or caulk has something to grab on to.
The next step is to fill the cracks with either caulk or epoxy. You’ll want to be sure to choose a filler that will perfectly match your travertine tile so the repair is seamless.
Squeeze the epoxy or caulk into the crack, and use something like a toothpick to push the material down into it to make sure it completely fills the crack. It’s okay if the caulk or epoxy overflows, as you can clean up the excess with a putty knife, razor blade or damp rag.
Now you’ll need to let the travertine tile dry overnight.
Hi Rita, Here's a DIY kit I found: https://www.walmart.com/ip/Miracle-Travertine-Limestone-Chip-Crack-Fill-Repair-Kit-w-Light-Dark-Custom-Colors-8oz-Dark-Filler-8oz-Light-Filler/217643970?wmlspartner=wlpa&selectedSellerId=15428&adid=22222222227151374259&wl0=&wl1=g&wl2=c&wl3=262863497759&wl4=aud-566049426705:pla-434080640845&wl5=9011817&wl6=&wl7=&wl8=&wl9=pla&wl10=125216413&wl11=online&wl12=217643970&wl13=&veh=sem&gclid=EAIaIQobChMI0bPCx7uM3wIVkonICh2zWgPEEAkYCiABEgIHzPD_BwE