Wǒ bèi xiàdào le.

我被吓到了。

I was scared.

Notes:

我(wǒ):I

被(bèi): a grammer word which shows the whole sentence is a passive one.

吓到(xiàdào): be scared

了(le): particel word which shows the action is done.

Example:

A: 我被吓到了。

    Wǒ bèi xiàdào le.

    I was scared.

B: 别怕，我在这里。

    Biépà, wǒ zài zhèli.

    Don't be scared. I'm here.