Yes, it might be the SD card reader or the SD card slot. The SD card slot might have got jammed or blocked by dust particles also. You can try to clean it by blowing air into it or with some folded paper to solve the issue.
Probably your SD card has got corrupt. Sometimes, an SD card behaves like a locked card, even if technically it is not. Then you need to remove the write-protection switch. You can visit this link if that is the case for further details: http://www.retrievephotos.com/article/fi...-memory-card-and-card-locked-error.phpm
Here’s a post which can help http://www.steves-digicams.com/knowledge-center/how-tos/troubleshooting-repair/troubleshoot-a-digital-camera-that-says-lens-error-on-screen.html#b Also check with these simple points 1. Cleaning of dirt or dust around the lens barrel 2. Check the batteries or use new batteries 3. Check that your Audio/Video Cables are properly inserted 4. Keep the camera with its back at the table and try the Autofocus
Check the card in some other camera; however as you have mentioned improper ejection of the card so there is a high chance of card corruption. In that case, try recovery software to get the content back. For the card, reformat and check if the card is detected or not.
It seems that the camera has frozen due to some reason. Try after sometime, and also properly eject the SD card. There may be some issue with the card and camera compatibility . Also check with the firmware update of the camera.
You can try memory card recovery software to retrieve data back from your SD card. Before initiating the recovery process, do not use the SD card for storing more information until the recovery process is complete. Considering that your phone is being recognized by your computer, connect your phone to the computer through a USB cable or card reader. Run the software Stellar Phoenix Photo Recovery Software. You can simply follow the instructions and copy the files to your desired destination.