[Windows Central Question]

i have a nokia lumia 520, the sim i have for my phone works with my phone however if the battery comes out suddenly (say i drop it) then the next time i turn the phone on it says that the sim is missing or invalid. this has happened several times and it always seems to take a whole load of various different efforts to get it to work again (such as putting a different sim in and then putting the right sim back in the phone). the problem is im not sure which is the one that works and was hoping you may have some idea why this is happening and what im suppost to do?

[RumoredNow]

I'm really not trying to be funny... Avoid dropping your phone so often.

If the battery pops out, the SIM is probably getting joggled pretty hard as well. Before you rush to pop the battery back in and get the cover popped back on, take a second to pull the SIM card out and then reseat it. Only after making sure the SIM is well and truly in the slot should you reseat the battery and power on the phone.

And here is the thing. Every time your battery pops out and the phone is running... That is hard on all your hardware and can lead to any number of software glitches. After one of these episodes take another minute to do a Soft Reset. With the phone powered on. hold the Volume Down + Power buttons until the phone vibrates and reboots. A Soft Reset will clear out your system memory and is a good way to smooth out glitches.