Why my Nintendo DSi is not showing games?

I have been using Nintendo DSi for 5 years and its game disc is damaged about 6 , 7 times is it normal or something bad ? I have changed my game disc ( from R4 v1.6 to R4 HDSC ) but not the memory card even its name ( MY DSi ) is shown the same just like before ( when connected to laptop through memory card reader ) i check my memory card it has 99 items and some space remaining ( about 90 kb ) and 94 threads which i just ignored but the very next day my DSi shows an error " Menu ? " i checked it again, it have 6 items no name no threads and memory space 4.03 kb remaining that is so irregular :( now what to do ? Help please