How can I get access to my lost contacts

Restore your device from a backup that has those contacts:

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

Be aware that restore is an all or nothing procedure. You cannot only restore contacts (for example) and any information on your device between now and when the backup was created will be lost.

Try -- Restore contacts, calendars, and more in Settings on iCloud.com - Apple Support.