^this.
If you don't have another phone, try it in a card reader with a computer. USB microsd readers are very cheap, especially if the data are valuable.
If instead you mean that the phone has pictures you want backed up but won't read the card, then copy them over usb to a computer, email them to yourself, copy to Dropbox, Google Drive or your preferred cloud storage service, use Google Photos to back them up, use WiFi to copy them to another device, or try a different card.