Hi @kcshyam ,
What is the make and model number of the laptop?
For starters, after 9 months not being used (or charged) the battery is most probably beyond recovery and will have to be replaced. Especially if it also got wet and was left inserted in the laptop
With HP laptops it is usually possible to get hold of a service manual which will help you to disassemble the laptop so that you can view the extent of the damage.
Once it has been assessed then decisions can be made as to what can be done, if anything, to try and resurrect the laptop to a working condition.