Laptop battery and other problems after prolonged sleep

[The antIMattEr]

Hey, I am using a HP laptop in the Pavillion series with a 4Gb ram, 1TB HD, Windows 8.1 5th gen. About two months back, I was watching a movie when I got a call that my father was in an accident. I paused the movie and went to the hospital without shutting down the lap. I had to remain at the hospital for 45 days. When I got back, I found that the battery has ran out. So I plugged it in and switch it On. The movie was still on at the same point I left it in... I thought that there would be no further problems but now there are many...
1. My laptop battery is draining a lot faster now...
2. The performance seems a lot slower now with random hang and a longer startup time
3. I had set GOM as my default video player. Now randomly th default video player setting seems to be erased and I have to set it again for every format.
4. My gaming performance too is down
5. Last night, I was watching a movie when the system hanged. The audio continued to run while the screen froze.
What should I do? I am thinking to format the lap and replace the battery. Any suggestions?

 

[webworkings]

When you get all the slowness, is it when running on battery alone, or is it on battery and plugged in?

 

[The antIMattEr]

On battery

 

[webworkings]

And does it perform fine when the charger cord is connected?

If so, your battery may be your problem. It may be in need of replacing due to not putting out enough of a charge to do what the laptop needs from it.

 

[The antIMattEr]

Thanks.. I will try it ( the working seems fine when it's plugged in)