Laptop wont charge after 4 years

stuck together in blue tape, could I replace that

Technically, yes, as someone put them there in the first place. But practically? No, risk of fire\damage, and even if you have the tech knowhow, buying the individual cells (if one manages to even source them) will very probably be much more expensive than getting a new complete battery.

Would buy a new battery fit it?

Would buy a new battery fit it?

Very, very probably yes. Lots of sources, as posted above by pebbly, or for example Duracell Direct Batteries - Laptop, Camcorder, Camera and Cell Phone , or an original from the laptop maker, or ebay for some cheap Chinese replicas (which may be ok... or not) etc. Good luck.

Okay I will try thanks