Hey - The easiest way to be sure if the issue lies with the phone or the SD card would be to borrow your sibling's or friend's SD card and try it out in the ZTE V795L and observe. If a different SD works and only not yours, then it will mean that yours has failed and sadly must be replaced. However, it the phone will not take either, then you might want to try and clean the phone's SD card slot's contacts in the following way.
- Turn off the phone and remove the battery
- Dip the SD card in methylated spirits and insert and remove the it repeatedly into the SD slot (and dip it in the spirits each time)
- Let it dry for 30 minutes when done and retry the SD card with the battery replaced and the phone turned on.
Unfortunately, if the ZTE V795L will still be found not to read any SD after this, then it will mean that the SD mechanism has failed and should be serviced or replaced. If the device is still under warranty, you can have either done for free by visiting the retailer you purchased it from with your proof of purchase and the box.