I can't manage to
Hay cosas que no logro entender.
There are things I just can't understand.
No logro deshacerme de este dolor de cabeza.
I can't get rid of this headache.
I can't understand it.
I can't manage to open the door.
No logro entender por qué cambió tan repentinamente.
I can't understand why it changed so suddenly.
— Vivir (1952)
Sé que lo tengo, pero no logro encontrarlo.
I know I have it, but I can't find it.