Is your freezer running at too cold of a temperature?
If so make sure the temperature control wasn't changed to a colder temperature - not likely, but definitely possible if you have kids at home. Next, take off the temperature control knob and test the control manually. It's possible that the knob (plastic cover) was taken off and placed back on in the incorrect position. If so, that means the number you place it at will not line up with the temperature you meant to select.
Is your freezer running a little too warm and not keeping food frozen? If so, there are two issues that could be happening here. First off, the door seal might be weak or it could have gaps or pinholes which are causing cold air to leak out and warm, humid air to flow in. Next, the problem could be to do with a faulty part that's causing the freezer to think it should be running its defrost cycle. As such, it might warm up intermittently which would prevent the freezing temperatures from holding.
What if your freezer is operating loudly or making weird noises? If so, many different little problems could be to blame that are easy DIY freezer repair jobs. First off, make sure the machine itself is not sitting unbalanced on the floor as this could cause it to vibrate more aggressively. Next, make sure the condenser and evaporator fans are not loose or clogged. If either fan is loose it can rattle around inside the machine, while if either are clogged it can cause the machine to work harder which can make it louder as well. Lastly, make sure the drain pain is not loose as this will cause a rattling noise.
You must be careful not to put too much food into your freezer. If it's overstuffed, the freezer might keep running all the time to make sure the contents are frozen. Figure out what the maximum capacity is for your freezer and do not fill beyond that level. If you suspect your freezer is too full, it's recommended to empty it and complete a defrost cycle before filling up with the appropriate amount. Afterward, make sure to never overfill the unit as it will lead to excessive wear and tear on its internal parts.