my 1998 chevy blazer, has no reverse/ and slow acceleration, everyone i talk to says replace the solenoid and get a transmission flush...... any advice

 

Are there any codes present?

No reverse and slow acceleration makes me think you no longer have all your forward gears. This can happen if the reaction sun shell inside the transmission breaks. This isn't exactly a common problem given the sheer number of 4L60E transmissions in operation, but can happen. If it does happen, it will take out Reverse, 2nd, & 4th gears leaving only 1st & 3rd gears.

 

2nd the sun shell.
My 2000 with the 4L60E did just that.
No reverse and 1st and 3rd only.

 

Mine only had reverse when it was warmed up & was slow to engage when cold to reverse - (blown seals) A quart of Lucas trans stuff helped that (for 1 winter) I eventually got it rebuilt.

Any codes?
Dumb question but is the fluid topped up? <-- in park, on level ground & trans hot. Slow acceleration might be low fluid - higher revs then motion.
I tried a complete trans backwards flush in hopes it would solve my reverse issue ^^^ like I said, I had it rebuilt, but that was my trans.

 

The only gear that's gone is reverse, all other gears WORK

They say it might be the solenoid

NOW IF ONLY THE REVERSE IS GONE,( I HAVE ALL OTHER GEARS) WHAT IS THE SAFEST STEPS TO TAKE, A MECHANIC SAID IT MIGHT JUST BE THE SOLENOID, BECAUSE MY REVS ARENT THAT FAR OFF, I DO UNDERSTAND THAT TRANSMISSION REPAIR IS A PAY DAY FOR ALOT OF MECHANICS, SO I'M TRYING TO FIGURE OUT WHAT COULD BE DONE

 

Well, here's the troubleshooting chart for No Reverse or Slips in Reverse. That doesn't explain your slow acceleration symptoms though... As you can see from the chart, there is no mention of a solenoid problem. It could be caused by a stuck 2-3 shift valve though.