I have not used my Apple Watch in a long time do I did a new battery for it
I haven’t used my watch in a long time I put it to charge but can not get it to come. On
Apple Watch, watchOS 4
Question marked as
Lithium iOn batteries which are fully discharged for an extended time often die completely and can't be brought back to life. If you can't get your watch to charge, then yes, you'll have to pay to have the battery serviced.
Depending on the actual model of watch, if it's too old, it may be an obsolete model and Apple won't service an obsolete model watch. See this link and enter the information to see if your watch even qualifies for service --> Apple Watch Service & Repair - Apple Support