It is common practice to leave Bluetooth open and the virus enters. But this is a completely wrong belief. Sometimes the song gets lost, I say it in two ways. When you insert the memory into the PC , it may show lost when inserted into the phone later. This is the problem of PC virus. It is caused by a virus called shortcut virus. The virus basically hides all the files in an unformatted folder and hides them. If you do not have this problem, then your memory is class 1 or 2 type. It's very slow because of some clutter (no matter how much you buy Class 10 in the store. It's not 10) and there are some memories that aren't properly programmed. Files are lost or corrupted in that memory. You should buy good quality memory. If you have an expensive Android phone, buy the u1 version of the memory. And virus is the short name of vital information resource under seize . In Bengal , very important information was confiscated. The explanation, however, involves big and different things. Ways to survive the virus Different people will talk differently but in case of mobile I would say , do not use antivirus. Download apps from the Play Store , not from outside. See what apps want permission. You can only save if you notice that the app's icon is clearly visible. But in the case of computers, there are different things that I can't explain in writing here.