2012 Mac book pro

Does the Magsafe LED light up?

Try an SMC Reset.

Here is an Apple article for troubleshooting Magsafe charging issues:

If your MagSafe cable or power adapter isn't working - Apple Support

Has the battery been completely discharged? Check the battery indicator light on the side of the laptop if you have the non-Retina model. If a Lithium-ion battery has been completely discharged, then it may prevent an Apple laptop from powering on or even charging. Sometimes you can disconnect the battery from the Logic Board and try powering on the laptop with just the charger. If it powers on, then you can try hot plugging the battery in and letting it charge at least 10% before powering off the laptop or disconnecting the power, otherwise you may cause permanent damage to the battery. You need to be careful not to let any metallic or conductive item or surface touch any of the internal circuitry or the laptop will be damaged.

If your Mac doesn't turn on - Apple Support describes all the steps you can take. Follow them all the way through to the end:

"If your Mac still doesn't turn on, please contact Apple Support."

See this link and if nothing helps, a 10 year old MacBook Pro likely needs to see the Genius Bar at your Apple Store -->