Yes, it matters. Placing the battery in the correct position ensures that the electrical circuit is completed and the flashlight can function properly. Typically, the positive end of the battery should be facing towards the bulb or LED.
remove and replace defective components
All should function properly if not I recommend seeing a health professional
flashlight
Electrical equipment that is defective should be where possible repaired and if not repairable it should be replaced.
flashlight
When it fails to function properly. You should never have to replace it, but it is possible.
A flashlight might not light due to dead or improperly inserted batteries, a faulty bulb, a loose connection, or a damaged switch. Checking these components and ensuring they are functioning properly should resolve the issue.
Need means that you would be better off if you get it. Neccessity means that you should have it (to function properly)?
If power goes out and you don't have a launtern or candle and you know where a flashlight is it is a good way to see things.
none perishable goods, flashlight, potable water, extra batteries for flashlight, underwear.
A properly placed shot should do a reasonable job of ceasing the life function of said sheep.