4g lite usb modem 551L works on laptop but not on desktop

go to this site:
https://www.apple.com/support/ipad/

find your model and follow then the instructions

here have some links which may help u
How to Unlock LG Google Nexus 4 E960
How to unlock LG Nexus 4 E960 sim unlock net

do a force close and reopen camera

It depends on your batterie's cells sometimes they die early if you don't or do use ya phone they will eventually die

check out this video

You may need to upgrade to a newer sim card. There have been changes recently, esp. with the broader adoption of, and newer versions of LTE. LTE is a whole different radio system than 3g or even 4g. (It is actually 3g on super steroids) I think a sim upgrade should fix the problem.

Run windows update, located in the control panel that you can access from the start menu. That should update any drivers you will need for the webcam. Once you've updated, return to the control panel and look at the "list view" or "icon view" (you should be seeing a ton of icons with text next to them). Find one that says something similar to "Cameras" or "Imaging device", and it should link to your webcam if it's installed.
The issue with the 4G modem is that your laptop probably doesn't have usb 2.0 ports. All that means is that your 4G modem won't be running at 100%. You can't really upgrade a laptops USB ports from 1.1 to 2.0 though, so there isn't much you can do in that respect. As long as the Modem is powering on and providing a signal, i wouldn't worry about it.

Yes, you can upgrade RAM of your Dell laptop. When you are upgrading purchase a RAM which is compatible to you laptop (or you may buy the same RAM but the speed are fast). I think 2g to 4g is enough RAM to run to your laptop.