Can't select board to compile

And I can’t flash Arduino Nano

Found 5 compatible libraries
Scanning dependencies…
No dependencies
Building in release mode
Checking size .pio\build\nanoatmega328\firmware.elf
Advanced Memory Usage is available via “PlatformIO Home > Project Inspect”
RAM: [= ] 11.3% (used 232 bytes from 2048 bytes)
Flash: [= ] 8.3% (used 2542 bytes from 30720 bytes)
Configuring upload protocol…
AVAILABLE: arduino
CURRENT: upload_protocol = arduino
Looking for upload port…
Using manually specified: COM3
Uploading .pio\build\nanoatmega328\firmware.hex
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x54
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x65
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x6d
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x70
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x3d
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x2d
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x31
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x32
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x37
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x2e

avrdude done. Thank you.

Happened a couple of days ago.
On another computer in Platformio , it works

Arduino Nanos are notorious for being shipped with either an old or new bootloader.

Since you are using board = nanoatmega328 already (which is “Old Bootloader” setting, 74800 baud), try nanoatmega328new instead (115200 bootloader baud).

Also see PlatformIO Registry.

I just updated everything.
Now it is flashing with these settings.

[env:nanoatmega328]
platform = atmelavr
board = nanoatmega328
framework = arduino

But I still can’t select a project. This interests me more

Try File->Open Folder and only open your project folder. You seem to have lots of projects in your workspace.

Thank you Helped.
The problem was in the workspace