Trying to locate my bitcoins I was working with a broker, now my "bitcoins" are in "blockchain", and I have no trace. 

How do I find them? How do I find said blockchain and bitcoins ?
I was working with a broker


There's no need to work with a broker to buy or use Bitcoin.

That's a bit of a red-flag. Often criminals call themselves brokers to trick people out of money.


  now my "bitcoins" are in "blockchain"


There are many businesses based on or around Bitcoin. I believe several of them use the word "Blockchain" as part of their name. One of them is Blockchain Access UK Ltd which is registered in London England. They were only registered 2 years ago. Their accounts are overdue which is not a good sign. They were nearly struck off last year which is also a bad sign. They are trading as Blockchain.com. Perhaps you refer to an account with them? Their website says their wallet service is provided by Blockchain Luxembourg S.A

There is no need to have an account with Blockchain.com, you can buy and use Bitcoin without having anything to do with Blockchain.com.

Blockchain is also the name used for the data-file that keeps track of Bitcoin movements. Every Bitcoin user has access to a local copy of the blockchain data file. Most wallets keep a copy or have access to a copy. But having this blockchain data file doesn't give you access to, or control over, any money. Generally you need a functioning wallet, a backup you can recover or something called a seed-phrase or a private-key. If you don't have any of these, you probably don't have any Bitcoin money.


  and I have no trace.


If you don't have account ID and password for Blockchain.com you almost certainly don't own any money at Blockchain.com.

If you don't have some sort of Bitcoin wallet program or app (there are many different Bitcoin wallets), you probably don't have any Bitcoin.


  How do I find them? 


You find Bitcoins in a Bitcoin wallet. If you don't have a wallet on your computer or phone but have an account with some online business such as Blockchain.com, get in contact with them through their website.

You can find the company behind Blockchain.com at it's registered address (see above).