Hi Onur_Bozkurt,
We’re happy to provide some assistance.
Since it sounds like you're missing notes and attachments from the Notes app, we recommend that you try the steps in the article here: If you're missing notes on your iPhone, iPad, or iPod touch - Apple Support
To perform the steps in the article, we suggested above, click and open the link, read the subheadings below, and try each step.
1) Check your account settings
2) Check your Recently Deleted folder
3) Use Search to find your notes
4) Manually search for your notes
The reason why we are recommending the steps above is because they will show you what to do if you're missing notes from the Notes app on your device.
If the original problem persists after trying our suggested troubleshooting steps, provide us with specifics on what you see for more help, and we will continue from there.
Thanks for using the Apple Support Communities.
Cheers!