Dell Inspiron n5050 battery backup and dvd problem

--Its been almost 2 years and my laptop is hardly giving my 30 minutes of battery backup.

Its also getting heated up soon and the CD/DVD is also not working.How many times i try to open the CD/DVD it does not open.

--Lately i have seen some screws missing from the laptop backside.Where can i find the screws nearby.

--Can anyone suggest me what are the things that i have to do so as to overcome the problem given above.