i have had pictures saved in photos since 2015 now all of a sudden all the pictures from my phone automatically uploaded to my computer which never happens without me plugging my phone into my computer and now 2 years worth of pictures were deleted

To things check:

• You may have opened a different Photos Library then before. Launch Photos while holding down the options key to bring up the library chooser dialog. Select a different library from the list of libraries. Are your photos thee?
• check the Preference settings for iCloud on your iPhone and in Photos Preferences >iCloud for your Mac. If iCloud Photos has become enabled on both devices, iCloud is keeping the Photos Libraries on both devices identical. Photos you delete on one device will be deleted everywhere.