Losing data access due to viral infections, spyware, keylogging, hardware failure, and just simply daily usage can ruin your day real quick. Most operating system data can be saved depending system health and circumstances leading up the loss.
Cellular Phone Sim cards can be compromised and data destroyed by a multitude of factors. External memory cards are susceptible to extreme heat and water damage. All forms of data is valueable to the user, but all electronics will fail, it is just a matter of when.
More likely than not, data is usually erased by accident. So ensuring that you can get it back is where we step in. Don't keep using a device you are having data loss on. get help as soon as you can, so it is not overwritten and data lost for good.