Repairs usually cost more than another camera so get estimates for repair and replacement.
If you want to try yourself try the usual google search for a "Service Manual" but these are rare. The usual is to try to clean the card contacts in the camera.
My JVC everio GZ-VX715BEK threw up a 'Memory Card Error' out if the blue after around 4years of use using Sandisk sdxc 64gb. I naturally thought the card had its day, but then found it was readable via my laptop sd slot.
I counted myself lucky that files were not lost, and purchased a replacement sandisk 64gb. To my suprise after inserting I got the same 'memory card error'! So I'm now worried the unit is the problem and would appreciate if anybody has ideas to resolve. I've done a factory reset, I'm unable to format the sd cards and this throws up 'format error'.