apple music has deleted my non purchased songs

How long were you not subscribed to Apple Music? Apple only keeps the account information for up to 30 days.

Boy, I would not have done it that way at all. It is very, very easy to transfer the iTunes library from one computer to another, either with Migration Assistant or with an external drive (even a flash drive if you are willing to do it in bits and pieces).

Are you sure you're not referring to iTunes Match?

iCloud Music Library: Understanding differences between Apple Music and iTunes Match - Apple Support

Subscribe to iTunes Match - Apple Support

Apple Music is a streaming service. You only have access to the music while you have an active subscription and not going forward at all.

Do you not have the 2500 tracks backed up somewhere else? They would have been used to upload to your cloud library. On your Windows PC?

So, you don't have the PC any longer?

You'll need a 3rd party solution for this. Take music FROM your phone TO your PC/Mac.

Your i-device was not designed for unique storage of your media. It is not a backup device and media transfer was planned with you maintaining a master copy of your media on a computer which is itself independently backed up against loss. To use a device with a different setup you transfer the old library from a computer or a backup directly to the new setup, not the device to the library. Media syncing is one way, computer to device, updating the device content to the content on the computer, not updating or restoring content on a computer from a device. The exception is iTunes Store media purchases which can be transferred to a computer.

Redownload or transfer your iTunes Store purchases from an iPhone, iPad or iPod to a computer - https://support.apple.com/en-us/HT201267 - "This feature works only for content bought from the iTunes Store." As of iOS9 it no longer does apps which now must be re-downloaded directly from the Store.

For transferring other items from an i-device to a computer you will have to use third party commercial software. See this document by turingtest2: Recovering your iTunes library from your iPod or iOS device - https://discussions.apple.com/docs/DOC-3991 Even this method may not fully recover what you had in the library originally. For example if in order to save space when syncing you had converted music files to a lower bitrate, or photos to a lower resolution, it is those lower quality files you will recover.

If you subscribe to Apple Music, tracks which are not part of content you have purchased or uploaded cannot be transferred and have to be downloaded directly from iCloud.