There may be two reasons for it

Either You know the concept but are not able to solve Problems due to lack of practice then You can learn it by practice, But looking for solutions is not a good habit, try solving simple ones and when You are able to solve simple Problems switch to the next level.

When You don't know the concept it is impossible to solve a problem so Please leave solving the problems and make Your concepts strong then only go for Problem-solving because directly going for problem-solving will make you feel a weak student which is not true.

Work upon this two things after Identifying Your issue You will be able to solve Problems.