There are a few different reasons why you might not be able to get comfortable in your bed anymore. It could be that your mattress is no longer providing the support that you need, or it could be that you're simply not used to sleeping in a bed anymore. If you're used to sleeping on a hard surface, like a futon or a floor, then it's going to take some time to adjust to sleeping in a bed again. Additionally, if you have any medical conditions that cause pain, such as arthritis, then it's possible that your bed is no longer comfortable because it's not providing the necessary support.
If you're having trouble getting comfortable in your bed, the first thing you should do is take a look at your mattress. If it's been a while since you've replaced it, then it's probably time for a new one. There are a variety of different mattresses on the market, so you'll need to find one that suits your needs. If you have a medical condition that causes pain, then you might want to look for a mattress that's specifically designed for people with chronic pain.
Once you have a new mattress, it's important to take the time to adjust to it.